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  • February 21, 2021 7:25 AM | Howard Ratsch (Administrator)

    Educational Blog

    This article represents the views of the author.  The article has not been fact checked by myself, the Board of Directors or any member of the USA Dive Club.

    Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that that might otherwise be infringing.

    Scuba Diving and Coronary Artery Disease - Advanced Diver Magazine

     By Dr. Douglas Ebersole, he is a cardiologist specializing in coronary and structural heart interventions at the Watson Clinic LLP in Lakeland, Florida.  He is also an avid technical, cave, and rebreather diver and instructor.  He can be reached at


    It is estimated that there are about 3 million certified scuba divers in the United States.  A large number of these individuals are middle-aged or older and at risk for coronary artery disease. Cardiovascular disease is the third most common cause of death while diving and remains the principal cause of death in the general population. The development of symptoms of angina, pulmonary edema, or sudden cardiac death underwater carries with it a much higher mortality than would the same event on land.  This article will review the workloads related to scuba diving, ways to assess risk in those with or at risk of developing coronary artery disease, and make recommendations to make scuba diving safer.

    Scope of the Problem
    In 2008, Denoble published a paper showing the annual death rate for scuba divers was 16.4 per 100,000 persons (1).  This was similar to the rate of 13 jogger deaths per 100,000 participants each year (2) or the risk of driving where motor vehicle accidents result in 16 deaths per 100,000 persons per year (3).  Thus, while the likelihood of dying scuba diving is quite small, understanding how and why these deaths occur is imperative.  Unfortunately, the ultimate cause of death while scuba diving is drowning, This does not give us a great insight into what led to the drowning.  Denoble reported on the causative process of 947 fatalities in an attempt to better define scuba diving fatalities (4).  He divided this into sequential components:  trigger, disabling agent, disabling injury, and cause of death.  Cardiac events constituted 26% of disabling injuries and these events were frequently associated with a history of cardiovascular disease and age greater than 40 years.   Thus, it looks like underlying cardiovascular disease is a major component in scuba diving deaths. 

    Workloads Associated with Scuba Diving
    It is clear that exercise itself is a cardiovascular stress and that the majority of non-traumatic deaths during exercise are cardiac in origin.  In most situations, diving is not particularly physically stressful.  However, there are times that due to current, waves, wind and other environmental stressors that demands during diving can reach 20 ml/kg/min (6-7
    METS).  Exercise capacity is reported in terms of estimated metabolic equivalents of task (METs). The MET unit reflects the resting volume oxygen consumption per minute (VO2) for a 70-kg, 40-year-old man, with 1 MET equivalent to 3.5 mL/min/kg of body weight.

    In the standard Bruce protocol, the starting point (ie, stage 1) is 1.7 mph at a 10% grade (5 METs). Stage 2 is 2.5 mph at a 12% grade (7 METs). Stage 3 is 3.4 mph at a 14% grade (9 METs)n and Stage 4 is 4.2 mph at 16% grade (12 METs).  This protocol includes 3-minute periods to allow achievement of a steady state before workload is increased.

    Thus, a diver with a steady state exercise capacity of 6-7
    METS can expect to manage most diving contingencies without concern for cardiovascular complications.  In most occupational exposures requiring increased physical activity, guidelines recommend maintaining workloads below 50% of maximal oxygen consumption.  Based on this relationship, a diver who is expected to minimize safety concerns related to environmental contingencies should have a maximum oxygen consumption of 12-13 METS – or about 12 minutes on a standard Bruce protocol exercise test.  Divers with peak exercise capacity below that level could expect to dive safely in low stress conditions such as warm water, minimal currents, and calm seas but could develop cardiovascular limitations under stressful diving conditions.

    Who is at risk?
    For divers older than 35 years, the dominant risk for sudden death is from coronary artery disease.  Although the incidence of coronary artery disease death is falling, the rising incidence with age makes this diagnosis the most important consideration when clearing divers who are middle-aged or above.

    One strategy to lower the risk of cardiovascular deaths would be to screen all adult participants prior to certification as most exercise-related cardiac events in adults are due to atherosclerotic cardiovascular disease. 

    The Framingham Risk Score is one of a number of scoring systems used to determine an individual's chances of developing cardiovascular disease. A number of these scoring systems are available online (5,6).  Cardiovascular risk scoring systems give an estimate of the probability that a person will develop cardiovascular disease within a specified amount of time, usually 10 to 30 years. Because they give an indication of the risk of developing cardiovascular disease, they also indicate who is most likely to benefit from prevention. For this reason, cardiovascular risk scores are used to determine who should be offered preventive drugs such as drugs to lower blood pressure and drugs to lower cholesterol levels.

    The population risk for divers could be predicted by using tools such as the Framingham Risk Score and potential participants with a specific score could be identified and excluded.  The problem with this approach is that atherosclerotic cardiovascular disease is prevalent among lower-risk subjects.  Also, extremely high-risk subjects are only a small part of the total population.  Consequently, the largest absolute number of acute events occurs not in the highest-risk subjects, but in the moderate- and lower-risk groups.  Excluding the highest-risk group likely have little effect on the total number of deaths.

    A Framingham risk score lower than 10% ( less than 1% per year risk) is considered a low score.  If a subject is assessed to be at low risk in general, that individual is not likely to have an acute coronary event while diving.  On the other hand, high-risk individuals (Framingham score > 20%) could be at considerable risk and should have further evaluation to evaluate whether diving will be safe.  Intermediate-risk individuals with a Framingham score between 10% and 20% should have further risk stratification to assess their risk for an acute coronary event while diving.

    In all individuals, regardless of risk, we should practice primary prevention of coronary artery disease.  The recommended performance measures for primary prevention are:


    Lifestyle/risk factor screening


    Dietary intake counseling


    Diabetes screening and management


    Physical activity counseling


    Smoking/tobacco cessation


    Weight management


    Blood pressure control


    Blood lipid measurement and control


    Global risk estimation with tools such as Framingham Risk Score


    Aspirin use in selected individuals

    Implementation of these measures requires performance of a careful history and physical examination, laboratory testing for lipids, and formal assessment of cardiovascular risk. 

    Performing stress testing in selected individuals, such as those with intermediate or high-risk Framingham score, is also an approach.   In comparison to younger individuals, far less attention has been paid to designing screening programs for older, usually recreational, athletes.  Few detailed pre-participation guidelines exist, and there is little reported experience in this age group.  Instead, most authorities focus on strategies used in clinical medicine for the early detection of atherosclerotic diseases, as these are the most common cause of death in this age group. 

    Since most individuals are asymptomatic, the history is often more helpful in identifying risk factors rather than symptoms.  Similarly, there may be few detectable abnormalities at rest or even with exercise as events are often due to spontaneous rupture of non-obstructive plaque.

    The American Heart Association issued recommendations for preparticipation screen in older athletes in 2007 (7).  This document recommends that older competitive athletes (>35 to 40 years) be “knowledgeable” regarding their personal history of coronary artery disease risk factors and family history of premature coronary artery disease.  Further, stress testing should be preformed selectively for individuals engaging in vigorous training and competitive sports, and who meet the following criteria: men > 40 years or women > 55 years with diabetes mellitus, or at least two risk factors or one severe risk factor other than age.  Finally, the document recommends education regarding prodromal cardiac symptoms, such as exertional chest pain.

    What about patients with established coronary artery disease?
    Patients with known coronary disease often have been subject to revascularization either by coronary artery bypass surgery or by percutaneous coronary intervention, usually with implantation of one or more coronary artery stents.  The degree of revascularization can determine safety in diving.  With complete revascularization, low-stress diving can be accomplished successfully, but diving in rough seas, fast currents or cold water could be risky.  There are many divers who have returned to diving after either coronary artery bypass surgery or stenting.  Success in return to diving is based on restored exercise capacity without ischemia after revascularization and choosing diving environments that do not produce excess stress on the cardiovascular system.

    Patients with significant reduction in left ventricular systolic function (LVEF < 35%) are at risk for exacerbation of congestive heart failure while diving.  Water immersion itself results in approximately 700 cc of fluid shift into the central circulation.  This could provoke congestive heart failure in patients with impaired left ventricular systolic function.  Additionally, most patient with LVEF < 30-35% will have impaired exercise tolerance when diving as outlined above.  For these reasons, patients with significant left ventricular systolic dysfunction should be advised against scuba diving.



    All adults should be evaluated for their risk of coronary artery disease prior to scuba diving


    Selected individuals with intermediate to high-risk Framingham scores should be referred for additional evaluation, such as treadmill testing prior to scuba diving.


    All individuals should practice primary prevention strategies to decrease their risk for the development of coronary artery disease

    1. Smoking cessation
    2. Blood pressure screening and management
    3. Weight control
    4. Physical activity counseling
    5. Cholesterol screening and management
    6. Diabetes mellitus screening and management


    Patient with coronary artery disease may begin (or return to) diving as    long as they have been revascularized with no ischemia on treadmill stress testing, have good exercise tolerance (defined as a maximum exercise capacity of 13 METs or an ability to sustain a workload of 6 METs), and have relatively preserved left ventricular systolic function.


  • January 22, 2021 9:30 AM | Howard Ratsch (Administrator)

    Educational Blog

    This article represents the views of the author.  The article has not been fact checked by myself, the Board of Directors or any member of the USA Dive Club.

    Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

    5-Year Trends in The Dive Industry: Scuba Gear, Dive Travel & Certifications | by Darcy Kieran | Scubanomics | Oct, 2020 | Medium

    DEMA recently published the results of its 2020 ‘Dive Behavioral Research Project’ from a survey conducted in 2019. A previous dive behavioral research was conducted in 2014.

    We have reviewed the results of both the 2019 and the 2014 studies to identify key pieces of information to help you manage your dive business. We are especially interested in changes between these 2 reports to identify trends in the scuba diving industry.

    About DEMA’s Dive Behavioral Research Project

    The goal of the project to analyze and understand the demographics and psychographics of scuba divers as it pertains to dive travel, scuba diving equipment purchases, and scuba courses.

    DEMA is the Diving Equipment & Marketing Association commonly referred to as our dive industry trade association.

    The data collection for the DEMA Dive Behavioral Research Project was done through an online survey.

    In 2014, 24000 divers responded to the survey with more than 2000 from Canada, about 13000 from the USA, and the remainder from countries across the planet.

    In 2019, only 9700 scuba divers responded to the survey with about 1000 from Canada, almost 5000 from the USA, and the rest from countries around the globe.

    Available Data Sets and Reports from The Dive Behavioral Research Project

    So far, DEMA released 2 sets of data from the 2019 survey:

    ·                      2020 results from all responding countries

    ·                      2020 results from USA participants

    A Canadian report is forthcoming.

    Shortcomings of DEMA’s Reports on Scuba Diver Demographics and Psychographics

    There is a serious issue with the 2019 survey besides the fact that the data set was significantly smaller (about 9000 respondents vs. 14000 in 2014).

    In the 2019 survey, more than 40% of the respondents were dive professionals: divemasters, assistant instructors, and scuba diving instructors. If we are interested in understanding the behavior of ‘scuba divers’, the 2019 data set is highly unreliable as almost half of the respondents were scuba diving professionals.

    We know dive professionals have a behavior that can be significantly different than that of the average Joe Diver. For instance, typically, scuba instructors dive more frequently and purchase more dive gear.

    Furthermore, when comparing the two sets of data (2014 vs 2019), we are facing a double problem in regards to dive professionals. In the 2014 study, less than 10% of the respondents were scuba diving professionals (divemaster and up) while there were more than 40% in the 2019 survey

    Therefore, we are facing the following 2 serious issues with this DEMA study on scuba diver demographics and psychographics:

    ·                      We can’t use the results to understand the behavior of a ‘scuba diver’ as both reports include dive professionals that are much more committed to scuba diving than the average scuba diver — which is especially true in the 2019 set of data with more than 40% of the respondents being dive professionals.

    ·                      We can’t fully rely on trends identified in changes from 2014 to 2019 since we would be comparing oranges to electric cars.

    It is fair to assume that dive professionals are more ‘core’ divers than ‘casual’. In fact, we see that the average number of dives completed by 2019 respondents is higher than it was in the 2014 study. Learn more about core and casual divers on Scubanomics.

    We’ve contacted DEMA to request a version of both reports (2014 and 2019) excluding all dive professionals, so we can better understand the behavior of scuba divers in regards to dive travel, scuba gear, and dive certification courses. Tom Ingram, head of DEMA, assured us that they “have plans for additional segmentation of the consumer data, including based on certification levels”.

    We hope DEMA will quickly produce 2014 and 2019 reports excluding dive professionals as this would be highly valuable to its members trying to understand the behavior of scuba divers.

    In the meantime, let’s see what information we can extract from the currently available reports mixing scuba divers and dive professionals.

    Key Scuba Diver Demographics and Psychographics 2014 vs 2019

    Two interesting trends identified in our review of these 2 studies relate to eLearning and rebreathers.

    Scuba Diving Certification Courses at Home, in a Resort, and via eLearning

    An assumption often discussed in the dive industry is that online learning is hurting local dive centers because it becomes easier to bypass the local dive center by completing the ‘theory’ part of the course and then flying to an exotic dive destination to complete the ‘pool’ and ‘open water’ parts of the scuba diving certification course.

    This appears to be partially true but not as major as we usually assume it to be.

    ·                      The number of scuba divers who have completed the ‘theory’ part of the course online with no interaction with a local dive shop before flying to a dive resort to complete the ‘pool’ and ‘open water’ parts of the course has increased by less than 1%: from 6% to 6.89%

    Meanwhile, we observe more significant changes in the following modes of completing the entry-level open water diver certification:

    ·                      The number of scuba divers who have completed all parts of the scuba course while in a vacation setting has declined from 23.9% to 18.7%.

    ·                      The number of scuba divers who have completed the ‘theory’ and ‘pool’ parts of the course before going on a trip has increased from 14.6% to 17.6%.

    Therefore, it appears there is no reason to fear that eLearning is encouraging scuba divers to bypass the local dive shop. On the contrary, eLearning seems to have increased the number of people completing the ‘pool’ part of the course at home before going on a trip.

    It may be more accurate to assume that the online high visibility of eLearning is actually encouraging people to find a local dive shop to complete their pool sessions locally. It’s reducing the number of people going straight to a dive resort to complete the entirety of the entry-level open water certification course.

    Increased Interest for Rebreather, Sidemount, and Freediving

    There is a huge shift between 2014 and 2019 on the next courses respondents were most interested in taking.

    In 2014, the courses in which respondents were most interested in taking next were rescue diver, wreck diver, divemaster, and underwater photographer. This significantly changed in the 2019 survey.

    Not only the list of courses has changed but the level of interest has skyrocketed.

    We must urge caution with these numbers. As mentioned earlier, the 2019 sample included more than 40% of dive professionals who are much more committed to scuba diving than the average Joe Diver.

    Typically, scuba diving instructors have been a good target market for tech diving as they are looking for more challenges after reaching the pinnacle of recreational diving. Therefore, it is unlikely that there is an 84% interest in rebreathers in the general population of scuba divers.

    However, these numbers do indicate a significant increase in interest toward tech diving (rebreather, side-mount, other mixed gas) and freediving.

    Freediving has seen steady growth over the last few years. Dive gear manufacturers carrying freediving equipment have reported growth in their freediving line of products even when scuba gear sales were down. Both Mares and Aqualung have made significant investments in developing their freediving line of products.

    It appears freediving is appealing to the newer generations. It is challenging without requiring you to carry all the cumbersome equipment required for scuba diving. It also makes for great Instagram look-how-cool-I-am pictures!

    Role of The Scuba Diving Instructor

    The most significant information source for scuba divers to decide what they want to do next remains the dive instructor and divemaster. Instructor/Divemaster gets a score of 4 on 5 while the local dive shop gets a 2.9.

    As we’ve stated before, there is a continued need for local scuba diving activities but the focus should be on the action of scuba diving, not on trying to sell dive gear in an understock retail store. We believe that in the years to come, the role of local dive instructors will become more significant while local dive shops redefine their mission and business model.

    Related article: A New Paradigm for the Scuba Diving Industry: It’s about diving!

    What’s Next?

    Once DEMA releases the 2014 and 2019 survey results for ‘scuba divers’, excluding dive professionals, we will be able to get more valuable information out of these reports.

    Subscribe to Scubanomics to be informed when this data becomes available.

    Don’t be left out: Subscribe to be the first to know about dive industry news and market data.

    Continue reading: Scubanomics Table of Content.

    Connect, to be our dive business buddy: LinkedIn | Twitter | Facebook

    Sign up for Scubanomics: Scuba Diving Industry 2021

  • December 20, 2020 8:13 AM | Howard Ratsch (Administrator)

    Educational Blog

    Coronavirus FAQs: What Is A Pulse Oximeter? Why Are So Many People Buying One? : Goats and Soda : NPR



    This article represents the views of the author.  The article has not been fact checked by myself, the Board of Directors or any member of the USA Dive Club.

    Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.


    Each week we answer some of your pressing questions about the coronavirus and how to stay safe. Email us your questions at with the subject line: "Weekly Coronavirus Questions." This week, we're considering questions about pulse oximeters.

    As the coronavirus continues to spread, a small medical device called a pulse oximeter has started to fly off the shelves. In fact, demand has spiked to such an extraordinary degree that you may not be able to buy one right now in your local pharmacy or online.

    What is the value of the device during this pandemic? Do you need to have one at home? The first question is relatively easy to answer. The second is a little more complicated.

    What is it?

    A pulse oximeter is a small electronic device that estimates the saturation of oxygen in your blood. You want a number in the 95% to 100% range. If the number drops to 92% or lower, that's a cause for concern. That's generally the level where a doctor might put you on supplementary oxygen and keep you in the hospital for observation.

    To come up with that percentage, the device clamps onto your finger or earlobe and shoots different wavelengths of light through the small capillaries, explains Dr. Richard Levitan, a New Hampshire-based emergency room physician who specializes in airway management. (For a more thorough scientific explanation, read this.)

    The term for low blood oxygen levels is hypoxemia. In this condition, your body's organs may not work right. Severe cases can interfere with heart or brain function.

    You've likely had your blood oxygen monitored by a pulse oximeter already. It's used during some physical exams and is considered essential during operations and intensive care. The devices also give your heart rate.

    Why are these devices suddenly getting so much attention?

    COVID-19 can bring on what's called COVID pneumonia — an infection in which the lung's air sacs fill with fluid or pus. And it's possible that someone infected with the novel coronavirus might be in the early stages of COVID pneumonia – including a drop in blood oxygen level — without experiencing any difficulty breathing.

    In such cases, a pulse oximeter might signal that you're in trouble before you realize it. That's what Levitan saw when he spent 10 days working in the ER at Bellevue Hospital in New York City earlier this month: Many COVID patients were already very sick with COVID pneumonia by the time they arrived. They were breathing rapidly, their blood oxygen levels dangerously low. Like mountain climbers, the patients had grown accustomed to gradually decreasing levels of oxygen and didn't realize they were in distress.

    Many of them said they only recently started feeling short of breath though they had experienced symptoms of COVID-19 for days. By the time the patients went to the hospital, says Levitan, the virus had already damaged their lungs, and many were in critical condition. He saw COVID pneumonia patients with oxygen saturation levels as low as 50 percent.

    "These COVID patients have adapted to this slow, insidious drop in their oxygen and they don't know it," he told NPR. "Then when they come in with shortness of breath, it is late in the process." In his opinion, a pulse oximeter could have caught the warning sign of low blood oxygen level earlier on.

    The disease "kills by silently causing [a decrease in] oxygen. When you come in late in the disease, which is basically everybody who we now have coming to the E.R., there is a high mortality," he says.

    Levitan says that in medicine, earlier treatment leads to better results — "and that's true of COVID, as well."

    Should you get one?

    Levitan thinks that in the midst of a respiratory pandemic, it makes sense to have a pulse oximeter at home – just as you might have a thermometer to track fevers. If you have symptoms of COVID-19, he says, like weakness, muscle aches or fever, you could use the device to measure blood oxygen levels.

    That 92% figure (or lower) is a sign that "you should get evaluated because this disease kills silently and you don't have to have significant shortness of breath" to be at risk. (Although people at high altitudes might have levels "in the low 90s and be fine," he adds.)

    Dr. Elissa Perkins, a professor of emergency medicine at Boston Medical Center, doesn't necessarily think everyone needs to buy a pulse oximeter. She worries that people will depend on the device's reading rather than calling a doctor if they're feeling sick.

    "I think it's a bit of a stretch to say that people should all have these at home," says Perkins, though she understands why people would want them.

    "In general, I think honestly, if people are starting to feel symptoms or feel even a little bit short of breath, they should probably contact their physician, if possible," she says. "Most places or many places at this point are offering telemedicine visits, telehealth visits and that can give a more thorough picture of what somebody is experiencing than just one number on a pulse oximeter."

    But she's not completely opposed to home pulse oximeters. She says if you have symptoms consistent with the novel coronavirus, using a pulse oximeter and consulting with a doctor can be a good strategy.

    She is concerned about one risk: People could be falsely reassured by good numbers into thinking they're not very sick. People with COVID "can get incredibly dehydrated, people can get very weak," says Perkins. "We've seen people fainting or passing out, who don't have particular respiratory symptoms and don't have shortness of breath. So it's another piece of data, but it's certainly not the only piece of data."

    There are other concerns. The reading can be less accurate if a person is wearing nail polish or artificial nails, has cold hands or poor circulation.

    It's possible to accidentally read the numbers upside down and panic over a seemingly eye-popping number. Or the device itself could be inaccurate.

    The American Lung Association chief medical officer Albert Rizzo issued a statement on Thursday advising against "buying pulse oximeters unnecessarily."

    "[U]nless you have a chronic lung or heart condition that affects your oxygen saturation level on a regular basis, most individuals do not need to have a pulse oximeter in their home," Rizzo said. "Most importantly, if you're interested in purchasing a pulse oximeter for home use, please discuss the necessity and use of the device with your health-care provider. A medical professional can determine if it would be helpful and also provide direction for interpreting the readings in the context of how you are feeling. Your pulse oximeter reading should be used along with your other symptoms such as shortness of breath, fever, fatigue, as parameters that would prompt a call to your doctor."

    Abraar Karan, internal medicine doctor at the Brigham and Women's Hospital and Harvard Medical School, is a proponent of caution as well when it comes to pulse oximeters for home use. He says it remains to be seen how predictive low oxygen levels are at correctly identifying patients who will have a severe course with the disease. He points to a recent study looking at 5,700 patients hospitalized with COVID-19 in New York City, which found only 27.8% needed supplemental oxygen at triage.

    And he shares Perkins' concern about people being either falsely comforted or unnecessarily alarmed.

    "What we don't want to happen is that people are in real distress but think that because their home pulse oximeter reads normal, that they are fine," Karan writes via email. "We also need to make sure that patients are using the pulse oximeter properly and that it is reading correctly — otherwise, you could have more people coming to the emergency room that may not need to be there."

    But Levitan says that kind of strain on ERs already happens when people interpret home blood pressure monitors or thermometers incorrectly. A much bigger concern, Levitan says, is people dying suddenly from COVID. And he doesn't worry that the device will just make people more anxious: "You know what? We've got fear. We've got anxiety. We need reassurance."

    Where do I buy one — and how worried should I be if there's a delay in getting it?

    If you do think a pulse oximeter would be valuable, Levitan suggests buying one from a medical source like a pharmacy rather than a random site on the internet – and it's a good idea to look for one that's been FDA-approved, if possible. You can go to the FDA's 510(k) Premarket Notification page here and search for "oximeter."

    It's possible to buy devices that haven't been approved for medical use, and such devices may be less accurate.

    Just a few months ago, it would have been easy to find consumer models costing about $30 typically on pharmacy shelves. They are often used by people with chronic lung disease who are taking supplemental oxygen to make sure they were getting the right amount of oxygen.

    With many pharmacies sold out, people are turning to sites like eBay and Amazon, where devices can be found in the $60 range.

    But Levitan says you shouldn't fret if you have to wait a few weeks to get one: "You know what? We have 12 to 24 months of this [coronavirus]," he predicts.

    He says in an age of respiratory pandemics, there is very useful health monitoring that people can do form home, in concert with a phone call to a medical professional.

    "We need to change the public perception of what health monitoring means in this age of respiratory pandemics," he says. "When you combine heart rate measurement, oxygen saturation and temperature, which are all three things you can do at home — and especially if you combine it with a phone call to your doctor or to your local emergency department ... that's incredibly informative."

  • October 21, 2020 7:08 AM | Howard Ratsch (Administrator)

    Educational Blog

    A New Business Model for a Redefined Local Dive Center

    COVID-19 accelerated changes happening in the scuba diving industry. How to be ready.

    By Darcy Kieran

    This article represents the views of the author.  The article has not been fact checked by myself, the Board of Directors or any member of the USA Dive Club.

    Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

    Retail, education, and travel industries are going through a severe transformation that started before the coronavirus pandemic. But the speed of change has accelerated in a COVID-19 world, and we need to keep up — or better yet, get ahead of the curve. The dive industry has been resisting changes to its business model for a while but can no longer withstand a tsunami of changing customers’ expectations and behavior.The global pandemic has reset the gameboard. How can dive businesses emerge stronger?

    I will look at the historical ‘distribution channel’ used to provide scuba diving lessons, dive gear, and scuba diving travel to scuba diving consumers. Then, I’ll look at how it is changing and how the current coronavirus pandemic is accelerating this evolution. Finally, I’ll look at what it means for your scuba diving business.

    Traditional Distribution Process for Scuba Diving Products & Services

    Historically, dive gear and scuba lessons have been provided to the consumer by ‘local dive shops’ (in ‘origin’ dive centers) and ‘dive resorts’ (in dive destinations). And way back then, dive travel was mainly sold by local dive shops.

    We’re talking, here, pre-internet. But the dive industry business model barely changed after the arrival of the internet. Consumers have changed, but not the scuba diving industry.

    Bear with me for a minute.

    Pre-internet, it was difficult for a newly certified scuba diver to independently select the best dive destinations for his/her annual vacations. The dive instructor in the local dive shop was the principal source of information. Scuba divers would come to the local dive center to check pictures of previous trips to different scuba diving destinations. And group travel was arranged by the dive instructor.

    Dive gear manufacturers, scuba diving training agencies, and dive resorts (dive destinations) were relying on local dive shops to reach consumers.

    The local dive shop was both ‘the front line’ and the gatekeeper.

    This model doesn’t work anymore, and you can expect this fact to be even more apparent post-COVID19.

    Noticeable Dive Industry Trends

    I will be looking at ‘trends’ but only as it relates to the distribution channels used to reach scuba diving consumers.

    Trends in Dive Travel

    Dive travel was the first scuba diving industry sector to bypass the local dive shop significantly. Knowledge about dive destinations is now available to all, on the internet — with much more in-depth knowledge than what the local dive instructor could provide.

    A local dive professional can’t be knowledgeable about every dive destinations in the world. In that sense, the internet is providing more value to the scuba diver. And ‘providing value’ is vital for a business to be sustainable.

    The next dive industry segment to bypass the local dive shop (in ‘origin’ locations) is scuba diving training.

    Trends in Scuba Diving Training

    Initially, online education (eLearning) was introduced as a means to let dive instructors do what they love best — be in the water — while the ‘boring’ part of teaching in-class could be done at home ‘in the comfort of your pink slippers.’

    What eLearning also created is an additional way to bypass the local dive shop. It is quite simple and convenient to proceed with the ‘dive theory’ part of learning to scuba dive at home — or at work! And, then, you get to your dream vacation destination where you will go underwater with a dive instructor, first in a pool, then in the magical ocean.

    I do not believe this provides the best value to the consumer. You end up with rushed ‘confined-water’ (pool) training sessions because there are just so many more exciting things to do under sunny tropical skies! Cutting corners is no way to fight our excessive dropout rate. But it is a challenge to be communicating to future scuba divers that it is more valuable to them (in the long run) to be learning to dive at their local dive center before going on vacation. Therefore, the trend toward going to a dive resort after eLearning is continuing to grow.

    With COVID-19, learning online instead of in-person has become the norm rather than the exception. It means that selling online courses will simply be easier than ever before. The coronavirus pandemic has accelerated the trend toward eLearning.

    Within the dive industry, we’ve seen training agencies rush to launch new online learning programs — about anything and everything.

    This eLearning trend is here to stay, and it means that it is becoming even easier to bypass the local dive shop.

    “The shift of learning from outside the home to inside has blurred the lines between learning and leisure.” McKinsey & Company

    To counteract this trend, local dive shops would need to reach local consumers while they are researching ‘scuba diving in Fiji’ or ‘PADI certification in Cozumel.’ Even with an unlimited online marketing budget, this would be a tough challenge. And local dive shops barely have any marketing budget!

    Trends in Scuba Gear Distribution

    This was the last leg on which local dive shops could still hope to stand. And there would be a lot to say about this! But I will move as quickly as possible to discuss ‘what to do about these trends.’

    Selling scuba diving equipment is the way most local dive shops have kept the lights on. The cycle of extracting money from clients in a local dive shop has, for the most part, be in this order:

    1.                     get them in with cheap scuba lessons,

    2.                    sell them overpriced dive gear, and

    3.                    book them on a dive trip to sell them more courses and equipment.

    With the beginning (training) and the end (diving) of this cycle bypassing the local dive shop, it is making it hard for local dive shops to keep their lights on! Scuba divers going straight to the dive resort are often not even aware of the existence of a local dive shop.

    And that’s only one trend.

    Another significant trend with dive gear has been a reduction in “sales per diver.” New scuba divers tend to buy less scuba equipment than their male baby boomer predecessors. This could be an entire post in itself. Make sure to subscribe to Scubanomics at the bottom of this article.

    Otherwise, a crucial development in retailing, of course, is eCommerce. That’s another trend we’ve seen surging during this worldwide pandemic. If you are not convinced, look at this graph from McKinsey & Company, a renowned US-based management consulting firm that advises on strategic management to corporations, governments, and other organizations.

    Just like eLearning is now part of everyday life, eCommerce is now more accepted than ever before. The dive industry can’t continue to ignore this fact.

    Why has eCommerce been so slow at being implemented in the dive industry?

    There are numerous reasons why eCommerce has been slow at penetrating the scuba diving industry.

    For one, dive industry leaders have continued to maintain that the local dive shop was, and ought to, remain the focal point of the industry. This was based more on nostalgia than on sound business principles.

    Can local dive shops operate an eCommerce site in a way that will satisfy today’s consumers? No. It would require an investment far superior to what a local dive shop owner could afford.

    When shopping online, consumers expect speed and convenience. Delivery has to be tomorrow, or earlier! And convenience means that a scuba diving equipment website should have all models in all sizes and all colors. Our internal distribution issues are none of their concern! On this front, as for dive travel, the internet is providing more immediate value to the scuba diving consumer than the local dive shop with its limited inventory and product knowledge.

    By pretending that local dive shops were able to continue to satisfy evolving consumers with a small, undercapitalized store, the dive industry has simply delayed the inevitable.

    Direct to consumer’ is how most dive gear manufacturers will try to offset a reduction in scuba gear sales in local dive shops. We can already witness it on Aqualung’s USA website, which is now a full-fledged eCommerce website.

    You can’t blame dive gear manufacturers from bypassing local dive shops — they were the last to do it after scuba diving certification agencies and dive travel.

    New Distribution Process for Scuba Diving Products & Services

    The local dive shop is no longer ‘key’ in reaching scuba diving consumers, and it is facing an existential challenge: What is the new raison d’être of the local dive center?

    A Redefined Local Dive Center

    First, let’s address the elephant in the room.

    I can hear you yelling at me through your smartphone screen! “Local dive shops are crucial for the diving community. They provide air fills as well as access and information on local dive sites.”

    Yes. I know.

    In fact, the current coronavirus pandemic is contributing to making local dive shops more of a dive destination than merely an ‘originator’ of clients for dive resorts in the tropics. But here’s the thing… That’s about scuba diving (the activity), not selling gear.

    Local ‘dive centers’ can still bring value to scuba diving consumers. Dive ‘shops’ provide very little value nowadays.

    Shaming people into buying dive gear from you because you are providing air fills was always a non-sustainable business scheme, and it is now utterly disconnected from reality.

    local dive shop sells six different products and services to scuba divers:

    ·                      Education / Training

    ·                      Equipment / Toys

    ·                      Experience / Travel (the activity of scuba diving)

    ·                      Rental Dive Gear

    ·                      Repair and Maintenance

    ·                      Refills

    The first 3 are the big ones. They are known as the 3Es or the 3 Ts.

    We’ve already discussed them. These products and services no longer need the local dive shop to reach end-users. And in many cases, the scuba diving consumers find more value when shopping outside the local dive shop. ‘Value’ includes convenience, product knowledge, and availability.

    We need to face reality: the 3 Es (or 3 Ts) are bypassing local dive shops, and that trend is intensifying.

    So, now what?

    You can only swim against the current for so long!

    The way to be successful in any business is by bringing value to consumers. And that could be in the last three services listed above. They can more hardly be remotely provided.

    It is conceivable that repair & maintenance and rental gear could eventually be provided from a centralized and remote location. But for now, these are services for which scuba divers may directly benefit from your local services.

    In other words, the local dive shop should drop the word ‘shop’ and work on being a quality ‘dive center’.

    Find a location near an appropriate local dive site. Setup a fill station for air, nitrox, and possibly trimix. Maintain quality rental dive gear to be used at that dive site by scuba divers and dive instructors. And offer repair & maintenance on scuba diving equipment.

    That is a ‘local’ business.

    I bet you’ll find that your profitability may even go up! Maintaining a retail store can be expensive.

    At that new dive center location, the focus is on scuba diving. That’s why you want to be near a proper local dive site. You may also select a pool, especially if it’s deep enough for scuba divers to practice their skills outside of scuba lessons.

    Of course, you may offer scuba diving lessons at that location, but the focus has to be on promoting ‘scuba diving’. The rest is just there to support the activity.

    And now is a good time to do it. People are looking for adventures close to home.

    Operating under this new business model requires that each of these services be profitable in itself. You can no longer rely on selling overpriced dive gear to subsidize the rest of your operations. It is not sustainable. It is preventing evolution in the dive industry.

    Promotional & Visibility Issue

    I know the owner of a local dive shop in an urban area who will be transforming his local dive business into such a dive center, dropping the in-store retailing of dive gear.

    The first problem you will encounter if you proceed like him is with dive training agencies and scuba gear manufacturers.

    To be listed on their website as a retailer or training center, you must be operating a store. Scuba diving training agencies and dive gear manufacturers are forcing us to maintain this non-sustainable model of a ‘local dive shop’ operating 6 businesses under one roof.

    So… The h*** with them!

    Your main source of new clients is likely to be Google and word of mouth.

    Word of mouth and good reviews will be easier to get if you concentrate your energy, money, and time at providing what you are good at, instead of trying to be everything to everybody. You got into diving because you love diving. Focus on that! That’s how you will be able to offer consistency in the quality of the experience under your personal craft brand.

    This is how you can plan to make a good living out of your passion for scuba diving.

    Furthermore, soon, the most significant part of your revenues should come from repeat business because your focus is on the adventure of scuba diving. Your business model is based on people diving locally. It is no longer based on quickly churning new entry-level scuba diving certifications to please the PADI and SSI of this world.

    Otherwise, Google is not like your dive training agency. You do not need to operate a retail store to be listed as a business on Google map. The same principle applies to Facebook. Take advantage of that!

    It will be good for you — and for the dive industry.

    It’s always been ridiculous that consumers searching how to ‘learn to dive’ on Google where being directed to ‘retail stores’ selling gear, while the actual location to take the scuba lessons was often miles (kilometers) from there!

    This is a business opportunity for your local diving business, and it can be an exciting transformational time for the scuba diving industry.

    A Future Scuba Diving Brand Based on The Experience

    The scuba diving industry is lacking a reliable worldwide brand. Scuba diving is a global activity, no matter where you live. And the experience you encounter under Brand A in dive destination X is usually totally different than the experience you discover under the same Brand A in dive destination Y.

    Since scuba diving is an activity where safety matters, scuba diving consumers need to have ‘trust’ in the quality of the experience they will encounter, everywhere they go.

    Eventually, we will see a scuba diving brand establishing itself as a provider of a consistent scuba diving experience at all locations. The focus will be on the consistency of the quality of the activity of scuba diving.

    Keep an eye out! That is the brand under which you would want your reborn ‘local dive center’ to be operating.

  • October 11, 2020 8:59 AM | Howard Ratsch (Administrator)

    Educational Blog

    Sunken Treasures: What Makes Divers Love Wreck Diving

     For some divers it’s...

    This article represents the views of the author.  The article has not been fact checked by myself, the Board of Directors or any member of the USA Dive Club.

    Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

    By Dive Training
    November 2, 2019

    The sport of scuba diving is certainly diverse, with something for everyone — at every depth and all experience levels. For some divers it’s captivating coral reefs with rainbows of colors and fascinating tropical fish. For others it’s the excitement of encountering sharks, rays and other large animals. Cave diving is another pursuit driven by the quest for discovery and an attraction to uncharted tunnels and passageways. But just what is it about shipwrecks? The interest in wreck diving seems to have increased, as evidenced by the greater number of wrecks deliberately sunk as “attractions” for divers to enjoy. Whether they’re sunk intentionally as artificial reefs or recently discovered archaeological treasures hidden in their watery graves for centuries, for whatever reason, shipwrecks draw divers.

    Wreck Diving and the ‘Why’

    Ships end up on the bottom of the ocean, lakes and rivers due to navigational errors, collisions, storms, wartime casualties or as a result of onboard mishaps such as fires or explosions. Also, there are more and more ships now being sunk intentionally to create artificial reefs. In general, shipwrecks in shallow waters and close to shore are the easiest to access and dived the most. Deeper wrecks and ones in more remote areas are dived the least. Many remain undiscovered or undived. With technological advances in sonar and magnetometer technologies, new wrecks are found every year in all oceans of the world. And more and more ships are also being sunk purposely to form reef environments to benefit divers and fishermen.

    The fact that shipwrecks offer a habitat for marine life is especially important in areas that have few natural reefs. The many flat, featureless areas of the Gulf of Mexico’s continental shelf make it prime for artificial reefing. The USS Oriskany sunk off Pensacola, Florida, in May 2005 and the Texas Clipper put to rest in Texas waters off South Padre Island are two examples of ships-to-reefs.


    Serious wreck divers seem to have an innate sense of exploration. It’s part of their core being. They live to venture where few if any have been. They yearn to unravel information and to discover what has not been known. To penetrate and explore the interior of a wreck, especially if few or none have done so, is a thrill that fuels the passion for discovery.

    For some that pursue wreck diving, historical interest is the driving force. Shipwrecks are like windows into the past. Researching the background and circumstances that led to the tragedy and then visiting the wreck site years, decades or perhaps centuries later can be like taking a journey through a time warp. Other divers are simply fascinated by the size of many wrecks and the major components and machinery that can be approached and viewed in a way that would never be possible before it sank. To swim past a colonial-era fluked anchor or to see an old crusty cannon laying in the sand can conjure thoughts of another era. Or to swim through an engine room, a bridge or crew quarters may make one wonder about the life on board the vessel years ago when it was underway plying the seas. Shipwrecks also offer many divers an environment to simply advance and hone their diving skills. A very large wreck upright in warm, clear water provides a perfect environment for several levels of development from Advanced Open Water, to various specialties and technical diver ratings.

    Serious wreck divers seem to have an innate sense of exploration. It’s part of their core being.

    Here are responses from several seasoned wreck divers when asked the “Why” question: “It’s the challenge and exploration of the unknown,” says Gary Gentile, famed wreck diver and author. “I always feel excited heading down the anchor line as I think about what I might discover inside the wreck, even if it’s a wreck I’ve dived before.” For Great Lakeswreck expert David Trotter, “It’s the desire to discover, explore and solve the mystery of ‘ships gone missing.’” Author of “Shipwrecks in the Sunshine State,” Michael Barnette says, “The factors that compel me to explore shipwrecks are curiosity, a fascination with maritime history, and a natural love of the ocean.” Barnette prefers “particularly deep or unidentified shipwrecks — places no one has been before.” United Kingdom wreck diver and explorer Leigh Bishop uses mixed gasses to “venture to areas where no dive charter has been before.” Leigh considers now “the Golden Age of shipwreck discovery around England” where he says there are more wrecks per square mile than anywhere in the world.

    Wreck Diving Training and Safety

    Wreck diving poses a unique array of hazards for any diver. Because so many wrecks constitute snags and obstructions on the seabed, trawler nets and high-test monofilament fishing lines are commonly strewn across wheelhouses and hulls. Now factor in low or no ambient light and an overhead environment that can easily trap a diver and prevent free ascent to the surface. Inside there may be sharp edges, loose cables, structurally unsound bulkheads, and a maze of passageways. Many wrecks fill with silt or mud that can easily stir, resulting in reduced visibility and serious orientation challenges. A diver trained only to an Open Water level has no more business penetrating a shipwreck than entering a cave.

    Wreck diving is an advanced skill and requires special training and equipment. But the necessary skill sets for wreck diving vary widely depending upon the specific circumstances: depth, water temperature, condition of the wreck, sea or lake conditions, and the degree of penetration, if any. Whereas an Open Water certification is adequate training to dive outside and around a shallow, tropical-warm water, well-lit, “trap-free” wreck in, say, Bermuda, to safely dive a deep, coldwater wreck like the Andrea Doria is the other extreme that requires special equipment and a training and experience level way beyond Open Water. Many wrecks at recreational depths are intermediate-level dives most of the time but as conditions change, namely current or visibility, they can transform into very advanced dives.

    The best advice is to do plenty of homework on wreck diving and get additional training before attempting wreck penetration.

    §                             Talk to the dive operator about the wreck or wrecks to make sure you have the proper skill level, experience and equipment for the dive.

    §                             Make certain you are properly outfitted for wreck diving and your gear is streamlined and snag free. Check for proper hose lengths and dive with only essential gear. Essentials while wreck diving may include two knives or cutting tools, primary and spare lights, reel and line, lift bags, alternate and redundant air supplies or more depending upon the dive.

    §                             Divers making repeat dives to a wreck need to be cognizant that the sea is constantly taking its toll. A section or a wreck that was sound and stable a few months ago may have become unstable over time.

    §                             Also, even after completing advanced and wreck diving courses, always take one step at a time in your progression as a wreck diver. Never make a dive changing more than one new variable. For example, if you are accustomed to warm-water diving, start with a wreck in warm water and begin by exploring only the outside of the wreck. Attempting a first-ever dry suit dive coupled with first-ever penetration is taskloading, and the load might just be too much too handle in one outing.

    Penetrating a wreck is a serious decision and should never be done on a whim without solid preparation, proper equipment and a well-thought-out plan. Wreck diving holds a wealth of opportunity for exploration and discovery. From the Great Lakesto Great Britain, and from North Carolina to the South Pacific, there’s a near endless list of wrecks waiting to be explored. Start training now and you’ll have a lifetime of adventure waiting for you as a wreck diver.

    Maritime History

    In all likelihood, the first boats built go as far back as the Stone Age when dugout canoes were used for fishing. Ancient civilizations relied upon rivers and seas for fishing, transportation and trade routes. As early civilizations developed, man realized that the most practical method for moving large quantities of materials or large numbers of people long distances was by floating them in a vessel. Ships clearly affected the course of our civilization. Historical records have tremendous value but artifacts provide a different insight to where we came from and how our ancestors lived their lives. Shipwrecks really are portals to the past. Many clues to where we came from remain hidden in ancient wrecks in the sea.

    The use of navigational methods dates back at least 5,000 years. In 3000 B.C. the ancient Egyptians developed the first vessels powered by wind. Egyptians used their wooden-hulled ships to explore the far reaches of the Red Sea. But the Aegean Seagets the credit for being the cradle of maritime history in the Western Hemisphere.

    “Before there were shepherds or farmers in Greece, there were sailors,” says George F. Bass, pioneer and father of underwater archaeology. In the early Bronze Age (3000 B.C.) sailors moved copper and bronze materials between Crete, Asia Minorand the Greece mainland. But by 2000 B.C. the Phoenician civilization had developed a maritime trading economy that spread across the entire Mediterranean Sea. They moved along the northern African coast returning with riches from Spain and Great Britain in ships with sickle-shaped hulls and straight-rising stem and stern posts. By the end of the first century and after a series of wars, the Romans became a major maritime power that controlled the Mediterranean, or “Inner Sea.” They were the most powerful empire in the Western Hemisphere and their elite demanded silk, spices and other exotic goods from the far reaches of that time, namely Egypt and Arabia.

    During the Middle Ages, Norsemen from Scandinavia used their vessel-building prowess to raid Britain and Ireland from the sea. Their double-ended designs with dragon-headed prows were constructed of overlapping oak planking and were powered by both oars and wind. When the wind was inadequate to fill the massive square sail, up to 20 oarsmen took over to power these sleek, efficient troop carriers.

    By the 15th century, Europeans were venturing out to sea establishing new commerce routes and trading partners. Soon after the historic Columbus voyage in 1492, European sailors recognized the wind patterns in the North Atlantic caused a clockwise sailing route to and from the New World. At that time the Europeans were in heavy economic competition for natural resources and were establishing colonies to secure their country’s power and wealth. The British, French, Portuguese and Dutch were all flexing maritime might to stake their claims. In 1578, Sir Francis Drake became the first to circumnavigate the globe in a galleon-design merchant ship. Later the sleeker, faster clipper ships were used to further expand trade between the West and the East.

    Maritime commerce in America’s Great Lakes has its roots in the days of the French fur trade. But it wasn’t until after the War of 1812 that permanent settlements flourished and commercial shipping expanded. Ship traffic picked up during the Civil War era and increased steadily through the early 20th century. Schooners, paddlewheelers, freighters, and passenger cruise liners crisscrossed the often treacherous waters of the Great Lakes. Over the years, thousands never made it to their final destinations.

    America’s first Continental Navy was established in 1775 with only six frigates. Naval ships and their designs were crucial in the early years of the United States, from the Revolutionary War and through the War of 1812 and the Civil War. Ship design progressed from sail and oar power to steam engines. Although prototype submarines date back to the late 1500s, it was during the 19th century that submarine designs were advanced for effective use in warfare. The famed battle of the ironclad CSS Virginia and the USS Monitor at Hampton Roads in 1862 had a major effect on the future of naval ship design and warfare.

    In the 1900s, modern internal combustion engines replaced steam engines and steel-hulled ships gradually replaced the wood-hulled fleets. Ocean liners replaced sailing vessels while the navies retooled their fleets with destroyers and armored cruisers. The Germans used submarine warfare in 1917 to strangle the Allied shipping commerce and World War I saw the first use of aircraft carriers.

    By the time the United States entered WWII, German U-boats were stalking and sinking Allied ships along the East Coast of the United States and Canada as well as in the Gulf of Mexico and the Caribbean. German submarine technology and production advanced rapidly. More than 1,100 U-boats were launched during World War II, but by 1943, the Allies were producing ships at a rate faster than the U-boats could sink them. Eventually new detection technologies and improved naval tactics resulted in fewer U-boat casualties. In the Pacific Ocean between 1942 and 1945, hundreds upon hundreds of ships were sunk in hard-fought battles across the Pacific southwest region.

    In July 1956, the Italian passenger liner Andrea Doria collided with the MV Stockholm near Nantucket, Massachusetts. It went down in 250 feet (76 m) of water that rarely is above 48 degrees Fahrenheit (9 degrees Celsius). In 1991 the maritime tragedy was the Salem Express and in 2006 it was the Al-Salam 98. Both were Egyptian ferries heavily loaded with workers and pilgrims that capsized in the Red Sea. Every year trawlers, tankers, ferries, cruise ships and even submarines end up wrecked underwater.

    Marine Archaeology

    Part historian and part scientist, archaeologists thrive on painstaking efforts to locate, retrieve, identify and catalog artifacts. They are trained to discover and preserve the lost and forgotten, whether buried in the ground or hidden on the bottom of the sea.

    Most marine archaeological sites are shipwrecks but some are the result of earthquakes. There are also ancient villages once located near the sea that are now underwater due to rising sea levels since the last Ice Age. For shipwreck sites, the ship, the cargo and the crews’ personal effects are all important for better understanding the social, economic and political conditions of the past.

    The chemical composition of the water environment, depth, temperature and level of light are all factors that can affect the condition of a wreck over time. Deeper wrecks tend to be better protected whereas shallow wrecks can be subject to commercial activities such as shipping, fishing, and oil and gas development. Shallow wrecks can also be affected by wave action from hurricanes and storms or from surf action. Salt water will rapidly corrode iron-based wrecks and artifacts. Sea organisms like the teredo navalis worm destroy wood and other organic materials. Fresh water is significantly less hostile than seawater. The cold, freshwater wrecks in the Great Lakes are incredibly well preserved, and many are almost fully intact after hundreds of years of submersion. The unusually low deterioration rate in this environment sustains an underwater museum for schooners, side-wheel steamers, passenger freighters and brigantines. Wooden barkentines from the 1800s remain upright with standing masts and secured yard arms.

    In the sea, a cover of sediment can preserve an old wreck by protecting it from organisms and oxidation. The dilemma many underwater archaeologists face is weighing the cost of a proper archaeological investigation with the potential value of the recorded recovery, and knowing that as the clock ticks, the underwater records are further deteriorating. Wrecks and artifacts removed from the ocean need to undergo a very special and lengthy preservation process. It can take years to fully stabilize materials that have been in the ocean. In 1960, George Bass, professor emeritus from Texas A&M University, was the first person to lead an excavation of an ancient shipwreck in its entirety underwater. But not all historically significant shipwrecks are excavated underwater. The French explorer Sieur de La Salle lost one of his ships in a shallow Texas Bay in 1685. More than three centuries passed before it was discovered buried in mud at a depth of 12 feet (4 m). The archaeologists devised a plan to excavate the wreck in place “dry.”

    From the antiquities to the modern era, shipwrecks are time capsules waiting to be opened. Some lay upright, while others upside down or resting on their sides. Over time many become buried in the silt and protected. Ones left exposed to the harsh elements of the sea eventually break into pieces, crumble and become a scatter of parts and pieces.


    Marine archaeologists and treasure hunters have been at odds for years. Archaeologists complain that treasure hunters disturb and often destroy wreck sites. They say treasure hunters often diminish their ability to systematically obtain knowledge from the remains of the ship. Marine archaeologists are especially critical of treasure hunters seeking financial gain over historical recovery and knowledge. Archaeologists often accuse treasure hunters and collectors of depriving them of finds and destroying critical information contained in the wreck. At best the treasure hunters are deemed ignorant of proper recovery and cataloguing techniques and, at worst, they are called looters.

    Many treasure hunters make the simple argument of “finders keepers” and rely on Admiralty Laws to support their salvage claims and treasure finds. With the spirit of adventure and itch for mystery fueling countless hours of research followed by costly searches of the depths, the finders argue they paid their dues and deserve the spoils for the risks taken. They claim that archaeologists overplay the “historically significant” card. They insist that many shipwrecks are no more than wrecked trucks or buses that had hulls instead of wheels. And it doesn’t have to be a gold or silver find. It may be an artifact as simple as an old bottle or a brass spike. Purist wreck divers argue for leaving everything as it is for others to see and for the next generation to enjoy, yet collectors often argue that if they don’t take it now, the sea eventually will. Teddy Tucker, Bermuda’s pioneer wreck salvor, once said that marine archaeologists “want to control everything.” He contends that many archaeologists recover important artifacts only to load them in warehouses instead of making them accessible to the public. Another complaint is that the marine archaeologists don’t do enough to educate the layman on the significance of wreck artifacts. The “treasure hunter versus archaeologist” arguments continue but it is inarguable that the search for artifacts of the past inspires many.


    A significant event in U.S. history occurred off the coast of Texas on January 11, 1863. The USS Hatteras, a 210-foot-long iron-hulled side-wheel steamer sent south to blockade the port of Galveston, sighted a suspicious set of sails in the distance. After a four-hour chase, the Yankee gunboat armed with four 32-pound cannons caught up to an unidentified black-hulled square-rigger. Initially the vessel in pursuit identified itself as the Spitfire under British flag but as soon as the USS Hatteras commander Homer C. Blake let his guard down, the black-hulled ship announced its true identity as the CSS(Confederate State Steamer) Alabama and blindsided the Hatteras with a point-blank broadside gun blast. In 13 minutes the USS Hatteras was on the bottom in 40 feet (12 m) of water. The Alabama suffered no damage. Two Union crewmen were killed. Today most of the ship is buried beneath the sand and mud 28 miles (45 km) due south of Galveston. Parts of its 500-horsepower walking beam steam engine and the tops of both of her paddle wheels protrude from the bottom. The Hatteras is a direct link to the Civil War and it has great historical significance as a naval wreck that sank under battle off the coast of the United States.

  • September 17, 2020 3:30 PM | Howard Ratsch (Administrator)

    Challenging The “Rules” of Scuba Diving: Because Not Everything is Black and White

    By Dive Training
    September 7, 2017

    This article represents the views of the author.  The article has not been fact checked by myself, the Board of Directors or any member of the USA Dive Club.

    Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

    If you’re like most divers, you’ve heard of — and perhaps adhere to — procedures that are considered “normal” within our sport. A few classic “always and nevers” include: always dive with a buddy; always do your deepest dive first; always wear a snorkel; never put your mask on your forehead; always end your dive with at least 500 psi remaining in the tank and — perhaps the number one scuba diving “never” of all time — never hold your breath.

    At first glance, these might seem like black-and-white concepts. Except, guess what? They’re not. At least not entirely.

    This might sound like I’m on the verge of committing scuba heresy, but please take a couple of deep breaths and keep reading, because in this article we’ll examine — and even challenge — several widely accepted “rules” of scuba.

    Rulemaking 101

    Human beings are social creatures. We essentially want to be accepted in society, to be viewed as normal. Without diving deep into sociological terminology, the concept of norms provides a key to understanding social influence in general and conformity in particular. Social norms are the accepted standards of behavior of social groups. Behavior that fulfills these norms is called conformity. Social norms often evolve into rules, which are defined as explicit or understood regulations or principles governing conduct within a particular activity. Rulemaking is one of the basic impulses humans have for organizing and simplifying actions.

    Norms — and the rules that often evolve from them — provide order in society. These are some of the reasons why most people, most of the time, conform to social norms and abide by certain rules.

    The thing about rules is that sometimes they are based more on folklore than fact. And sometimes rules change when new facts are revealed. Take Nitrox diving, for instance. When it was first introduced decades ago there was a big hubbub about it being a dangerous “voodoo” gas that could potentially kill divers. It was condemned by the major scuba diving magazine at the time and banned at popular dive destinations. Now we know differently and divers everywhere are safely using Nitrox.

    Those who challenge social norms and set out to bend or even break the rules sometimes find themselves at the center of controversy. They often get branded as troublemakers and might even find themselves at odds with the law. However, these people also tend to be significant change makers.

    Let’s examine some commonly accepted scuba rules regarding equipment and dive practices that might be worthy of bending. If nothing else, they’re worth pondering.

    Equipment-Related Rules

    Always wear a snorkel.

    The snorkel is a required accessory for scuba diving students and their instructors to wear during training dives. But once certification requirements are fulfilled there are instances when wearing a snorkel attached to the mask can prove problematic. For instance, it presents a potential entanglement hazard when scuba diving in overhead environments, such as wrecks or caverns. In addition, it can create drag when diving in a current.

    Still, a snorkel is a useful accessory when at the surface. In recent years several innovative scuba equipment manufacturers have developed flexible snorkels that roll up small enough to fit in your buoyancy compensator (BC) pocket and/or fold into their own “shell” carrier that clips to the BC. For this reason, I’d like to edit the “always wear a snorkel rule” to read, “always carry a snorkel.” When the dive is done and you’re ready for a surface swim, locate your snorkel, attach it to your mask and you’re good to go.

    Never put your mask on your forehead.

    Okay, this one is a pet peeve of mine. I wrote about it in the May/June 2016 Final Check column, titled, “What It Looks Like When … Safety is Your Best Practice.” Somehow, somebody got a whole bunch of divers believing that placing the mask on the forehead is the international signal for “diver in distress.” Except, that’s just plain wrong.

    It is not uncommon for a panicky diver to jettison the mask and regulator. This action is a panic response, which is an indication, or a sign, that the diver is experiencing a problem. However, it is not a signal, as in “if you are having a problem, put your mask on your forehead to signal you are in distress.” If you surface from a dive and need help, signal, “I am in distress and need help” by waving one or both arms above your head. (It’s also a good idea to use an audible signaling device such as a Dive Alert™ or whistle.) There are plenty of instances when a completely happy, non-panicky diver might place the mask on his or her forehead without incident. That said, there are times when placing the mask on the forehead might not be a good idea, like when you’re in choppy seas. If your practice is to prop your mask on your forehead upon surfacing from a dive instead of leaving it in place, you run the risk of having the mask dislodged by a wave — and getting lost to the deep.

    No gloves allowed.

    Believe it or not, this is actually a hard-and-fast rule in many tropical dive destinations. In some locations, divers caught wearing gloves while scuba diving, face stiff penalties. (Fines may also apply to dive operators.) The idea behind this rule is that wearing gloves encourages divers to grab — and subsequently damage — delicate corals, whereas barehanded divers will think twice about doing so because they risk being cut by sharp coral or stung by stinging marine creatures.

    I wholeheartedly support the environmentally conscious intent behind this rule. However, I do not agree with the practice of strictly prohibiting divers from wearing gloves. Some divers have medical issues requiring them to protect their skin from exposure to sunlight, have clotting issues that turn a simple cut into a medical crisis or run risk of infection due to a cut. These folks shouldn’t need a note from their doctor in order to be allowed to wear gloves while diving.

    This month’s Final Check column, “What It Looks Like When … You Are Careful What You Touch,” addresses the potential danger of grabbing a marine-life encrusted mooring line during a safety stop. While no one associated with this magazine promotes the wanton destruction of marine life, we think the ban on dive gloves goes a bit too far. Instead, we’d like to see industry stakeholders continue to promote environmentally safe scuba diving practices that encourage divers to avoid touching corals, while still allowing them to wear gloves when needed. For instance, a diver can easily stash a pair of gloves in a BC pocket and retrieve them for use when grasping an encrusted mooring line during a safety stop.

    Always turn the tank valve back a quarter- or half-turn.

    This one’s been around forever. And it’s wrong. Don’t do this. Instead, always turn the valve all the way on and leave it that way. Do not turn it back at all.

    Apparently, the reason this practice got started is because someone decided that divers might inadvertently “strip” the valve by attempting to turn it on after it was already on. Tank valves are pretty hardy. The chances that you’ll damage a valve are slim. However, if you partially close the valve and then descend to a deep depth, the partially closed valve could restrict the airflow from the valve, making it difficult for you to breathe while on a deep dive. To avoid having problems with restricted airflow at depth always turn the valve all the way on. You are more important than a tank valve. Never turn it back a quarter- or half-turn.

    Ruling How We Dive

    Never dive alone. Always dive with a buddy.

    When recreational scuba diving first started, the relatively crude nature of early dive gear made it necessary for divers to help each other out. The buddy system was born of common sense. It’s hard for many new divers to imagine going on a dive without a BC, submersible pressure gauge (SPG), alternate (or redundant) air source or a dive computer, but all these devices were absent from early dive training. They simply hadn’t been invented yet. Keeping this in mind it’s easy to imagine why having a buddy was considered mandatory. In fact, buddy breathing — sharing one tank and regulator between two divers — was a critically important skill taught in early scuba classes. Over several decades, equipment advances have enabled divers to become safer. And more self-sufficient. Thanks to the development of alternate air sources and redundant air delivery systems, and the fact that buddy breathing itself could be inherently dangerous, the buddy breathing skill has been purged from today’s scuba diving training courses.

    Where it was once considered risky and even foolhardy to solo dive, the practice is slowly gaining acceptance. Several major scuba-training agencies offer Solo Diver and/or Self-Sufficient Diver certification courses aimed at increasing diver independence and reducing an individual’s dependence on the buddy system.

    However, despite advances in equipment and training, the issue of solo scuba diving remains controversial. Some industry experts argue that buddy diving can carry with it greater potential risks than solo diving. Some recreational divers agree, complaining about being randomly paired with a buddy they’ve just met. Some dive operators prohibit solo diving, insisting that their customers be in buddy pairs or teams, often on guided dives. Still other dive operators allow solo diving for those qualified and equipped to do so.

    A word of advice for those who wish to solo dive on a charter: reach out to the dive operator in advance to discuss your solo diving preference. Be willing to provide proof of your solo diving experience. Recognize that the dive operator has the right to deny your request to dive solo and insist that you abide by their stated operational policies. If this is the case, you have the option to seek the services of a dive operator that welcomes solo divers.

    It’s also important to note that in certain areas, such as city, county, state or national parks, solo diving might be prohibited. It pays to read the fine print when planning a solo dive inside park waters.

    On a personal note, I’ve made my share of solo dives, usually on shallow sites not far from shore. I have enjoyed the freedom and solitude of solo diving without any problems. I think those who are willing to accept responsibility for their own safety as a solo diver should be respected rather than viewed as reckless.

    No matter where you stand on the issue of solo diving, I think we all can agree that every diver should train and equip for self-sufficiency and be able to handle potential problems that might arise during a dive.

    Always do your deepest dive first.

    This rule was considered law for many years, and it is still widely practiced today despite the development of sophisticated dive computer algorithms and new research into decompression sickness. Dive Training’s Senior Editor Alex Brylske revisited this topic earlier this year in an article titled, “Deepest Dive First? The History and Science Behind How We Plan Our Dives,” which ran in the January/February 2017 issue. Here is an excerpt from Brylske’s article:

    “The issue of reverse profiles is sometimes confusing because the term actually can have two meanings. First, a reverse profile can refer to a series of repetitive dives where the deepest is not the first in the series. On the other hand, it can also describe a single multilevel dive that doesn’t follow the ‘stair-stepping’ procured described earlier; and the diver finds him or herself in the deeper phase of a dive after completing a shallower segment. Both procedures violate the deep-first rule.

    It may surprise you to learn that the deep-first rule is a relative newcomer to the diving liturgy, traceable only back to the 1970s. The story is also an interesting lesson in the history of scuba diving.

    A popular assumption is that the recreational scuba diving community simply adopted the deepest-first rule from the US Navy. Such an assumption seems entirely reasonable given that the USN Tables were the first standard for recreational scuba diving. The problem is, it’s not true. The US Navy does not now, nor did it ever, have any prohibition against reverse profile diving. In fact, one of the example dive table problems an older version of the US Navy Diving Manual involved a reverse profile. Likewise, there is no such prohibition in commercial scuba diving. So where did the rule come from?

    The first suggestion to make the deepest dive first appears to have been offered in a relatively obscure reference — and only as a suggestion — by a researcher named Dennis Walder in 1968. His rationale was that by making the deeper dive first, one might crush “silent bubbles” — assumed progenitors of decompression illness — making the development of bends less likely on that and subsequent repetitive dives. But this was based primarily on theory and informed speculation, not empirical evidence. Moreover, no reference to any deep-first guideline appeared in any recreational diving literature until 1972, when the following statement was published in PADI’s Basic Scuba Course Manual (a curriculum segment of the then-current PADI Instructor Manual): ‘One very important rule — WE ALWAYS MAKE OUR DEEPEST DIVE FIRST when using the dive tables.’ No rationale was provided, though examples were often included during training showing the aforementioned advantage of avoiding decompression stops.

    By the 1980s ‘deep dive first’ was growing beyond a recommendation.

    By the 1990s, the mantra of-deep first was firmly ensconced in diver training materials as well as in the psyche of divers; and no prudent diver even considered violating the warning. But by this time dive computers had become standard equipment, and whether by accident or intention, divers were making — and getting away with — repetitive and multilevel reverse profile dives.”

    Brylske sums it up by saying, “In all probability, the deep-first rule might never have been challenged had it not been for the widespread use of dive computers. Although the rules say otherwise, no dive computer in existence explodes, calls the police or ceases to function if the user engages in a reverse profile dive.”

    Always end the dive with at least 500 psi remaining in your tank.

    This statement is uttered during practically every pre-dive briefing in locations all over the world. The rationale behind it is solid; divers should plan their dives well and monitor their gauges carefully to avoid running low on — or out of — air. And responsible dive guides should remind divers to monitor their air supply to avoid an out-of-air emergency.

    However, in some instances, well-meaning but overzealous divemasters might take it a bit too far. I’ve heard divemasters jokingly “threaten” divers with penalties, like, “You’ll owe me a 6-pack,” if they surface with less than the mandated 500-psi.

    If a diver is nearing the end of a dive and needs to consume air below the 500-psi mark in order to complete a safety stop, the diver should feel comfortable doing so without fear of reprisal by the dive crew, because there’s simply no place for shaming in scuba diving.

    Never, ever make contact with the bottom.

    If you haven’t wanted to burn me at the stake by now, here goes. Over the years we have occasionally published photos of divers kneeling onthe bottom. This usually results in a flurry of reader letters calling Dive Training out for promoting bad diving practices. Most recently, in the July/August issue, we ran cover photos that feature two divers standing/kneeling on a sandy bottom while on a shark dive at the famous “Tiger Beach” dive site off Grand Bahama Island. I am one of the divers pictured in the photo. I’m not sure where or when the “never touch the bottom” rule got started, but I can assure you there are several instances in which kneeling in the sand is an accepted practice. Tiger Beach is a perfect example. The site is shallow (less than 30 feet [10 m]), there’s usually a moderate current running — and the water is filled with sharks.

    For these reasons, attempting to stay neutrally buoyant, kicking hard against a current while hovering a few feet off the seafloor and keeping an eye on the sharks would be impractical — and potentially dangerous. Here, kneeling in the sand is the best practice. Dive operators in other parts of the Bahamas, Fiji, Tahiti, the Maldives and other popular dive destinations follow this practice.

    Those who teach underwater photography know it is better to position beginning photographers in a sandy patch adjacent to a reef than to have them crashing into the coral while just starting out with a camera. Yes, the sand biome contains marine life, but in most instances it is not as delicate as fragile corals. A diver who carefully settles on a sandy area will have minimum impact on the environment.

    In parts of the world where strong currents are common, dive operators instruct divers in the use of “current hooks” as a means of having minimum impact on the environment. A current hook, as its name implies, is a large hook attached to a short length of line with a clip at the other end. The clip attaches to a D-ring on a diver’s BC. Divers learn to hook into an area of coral rubble in order to stay put in a strong current. By using the hook, they avoid grabbing the bottom with their hands.

    Here’s one more real-world “contact” scenario: If a diver accidentally ventures too close to the reef, rather than kicking to attempt to move farther away, using a one-finger touch of a dead or algae-covered section of reef to carefully push up and away from the reef is likely to prevent the diver from damaging living coral.

    The “look but don’t touch” mantra is ideal, but there are instances when it’s not always practical. What I’m suggesting here is careful and conscientious contact with the bottom (and with dead sections of coral) when conditions warrant it.

    Always breathe continuously. Never hold your breath.

    As I mentioned earlier, this is arguably the “number one rule” of scuba because breath holding while scuba diving can lead to serious injury, even death. However, there’s a however here.

    I bring it up in honor of a diver I met years ago. We’ll call her Janet. I guided Janet on her first recreational dives after she got certified. She bought a weeklong dive package and her first day of diving with the dive center where I worked went flawlessly. The conditions were perfect and Janet appeared comfortable in the water. I took a few underwater photos of her, smiling and signaling “OK.” She said she had a great time.

    The following morning, she was waiting at the dive shop very early when I showed up for work. She told me she wanted to cancel her dives. When I asked why, Janet explained that she’d been awake most of the night because she was worried that she might have accidentally held her breath at some point during the dive the previous day. She said, “My instructor drilled it into our heads, ‘If you hold your breath, you will die,’ and I’m just afraid. I can’t remember if I held my breath or not, but I don’t want to die.” I explained in great detail why divers should breathe continuously and avoid holding their breath. When I was finished, Janet decided not to give up on scuba diving after all. She sat out the morning dives in favor of some sleep, but was back out on the boat later that afternoon.

    So, here’s my little secret about breath holding while scuba diving. I often do it when taking underwater photos. I admit this not to encourage any diver to adopt the practice of holding their breath while on scuba, but rather to add some clarity to the breath-holding issue. If you’re like me and you sometimes briefly hold your breath while stationary, it is unlikely you will risk a lung-expansion injury. The key here is the word “stationary,” as in remaining in place and not ascending. If you hold your breath while ascending, you do indeed put yourself at risk of a potentially serious and possibly fatal lung-expansion injury. This is why scuba instructors drill it into students’ heads to “breathe continuously and never hold your breath.” But if you’re like Janet and you might have briefly forgotten to breathe continuously just for a second, say, when posing for a photo underwater, chances are, you’ll be okay. Still, do as your instructor insists. Breathe continuously and avoid holding your breath.

    A Question for You

    If you’ve read this article all the way to the end, thank you. I hope you found it thought provoking. However, the take-home message I wish to leave you with isn’t about following rules. It’s about asking questions. Asking why we divers do or don’t do certain things is important. It’s how we learn and understand and it’s also how we grow. Not everything is black and white. I want to encourage you to ask the questions and find the answers and then question the answers if they don’t sound right. This is ultimately how we advance our sport, making it safer and more enjoyable for all.

  • August 22, 2020 8:32 AM | Howard Ratsch (Administrator)

    Educational Blog

    Health for Diving: A Primer on Diabetes

    By Robert N. Rossier
    February 13, 2018

    This article represents the views of the author.  The article has not been fact checked by myself, the Board of Directors or any member of the USA Dive Club.

    Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

    We all know there are medical factors that can prevent people from diving. Epilepsy, various heart conditions, loss of consciousness, pneumothorax, some chronic diseases and even some forms of anxiety can spell trouble that may be incompatible with diving. But over the years, the list of contraindications has narrowed, allowing more to enjoy exploration of the underwater world.

    One condition that has prevented some people from becoming divers is diabetes. Diabetes affects the body’s ability to produce or respond to insulin — a hormone controlling the metabolism of carbohydrates. The result is abnormal carbohydrate metabolism leading to elevated glucose levels in the blood and urine.

    While this might sound innocuous, the long-term effects of diabetes are dead serious. Diabetes takes more lives than AIDS (acquired immunodeficiency syndrome) and breast cancer combined, claiming one American life every three minutes. Diabetes is a leading cause of blindness, kidney failure, amputations, heart failure and stroke. What’s more, the incidence of diabetes is growing. According to, the number of reported cases of people living with diabetes has jumped nearly 50 percent in the past decade and it now affects more than 29 million Americans. On a global scale, diabetes afflicts more than 380 million people, and the World Health Organization estimates that by 2030, the number of people living with diabetes will more than double. Clearly, diabetes is a growing health risk and one that could affect our ability to dive safely. But, at least for some, the door has been opened for scuba diving with diabetes — that is, if the proper conditions are met and the proper protocols are followed.

    Diabetes is categorized into two primary types, referred to as Type 1 and Type 2. In those with Type 1 diabetes, the pancreas does not produce insulin or it produces insufficient insulin to meet the body’s needs. Individuals with Type 1 diabetes must receive insulin injections regularly in order to metabolize blood glucose (blood sugar). In the more common Type 2 diabetes, the body may not produce enough insulin or the insulin does not trigger the cells to allow proper metabolism of glucose.

    Type 1 and Type 2 diabetes are the most common forms of the disease but other forms exist. Many individuals are also diagnosed with pre-diabetes, a condition in which blood sugar is high but not significantly enough to warrant treatment. Unless changes are made to diet and exercise, those with pre-diabetes are likely to join the ranks of individuals diagnosed with diabetes.

    To understand the effects of diabetes, we need to have an understanding of some basic human biology. In a normally functioning body, a number of metabolic reactions occur in response to eating. First, the digestion process in the stomach breaks the food down into glucose (a form of sugar), which enters the blood stream and is transported to cells throughout the body. The hormone insulin is secreted by the pancreas, which triggers the cells to allow glucose to enter. Through a process called glycolysis, the glucose is broken down in the production of a molecule called ATP (adenosine triphosphate), which is the source of energy in the cell. Also in response to eating, the cells also synthesize and story fatty acids and proteins. These are all critical functions for a normal, healthy body.

    For the person with diabetes, this process simply does not work properly. Type I diabetes is actually an autoimmune condition. The immune system destroys the beta cells in the pancreas, which are responsible for the production of insulin. And without that insulin, glucose does not enter the cells and they run out of energy.

    For Type I diabetes, those affected must receive injections of insulin at the appropriate times to control blood glucose levels and allow cells to receive the needed glucose. Eating the right foods at the right time can also help control blood sugar by controlling how much glucose is produced through digestion. Other factors including exercise, stress and general health also affect the body’s need for insulin, so getting the correct timing and dosage for insulin injections can be a challenge.

    In Type 2 diabetes, the pancreas has a deficiency of beta cells that create insulin, making it unable to supply enough insulin to the body. In addition, insulin receptors at the cellular level may not respond properly to insulin, limiting the amount of glucose entering the cells and allowing blood glucose to remain elevated. Controlling diet is also important for those with Type 2 diabetes to prevent spikes in blood glucose. Medications are available to help maintain an appropriate low level of blood glucose. For some, additional medications may be available to increase insulin production by the pancreas.

    The factors that determine blood glucose levels fluctuate greatly throughout every day, so for a Type 1 diabetic, determining the proper dose of insulin to take can be a complex and sometimes delicate balancing act. Too much insulin means the body consumes too much glucose, which can drive blood glucose to a dangerously low level. This low blood glucose condition, referred to as hypoglycemia, can sometimes be fatal if prompt corrective action is not taken.

    With too little insulin, blood glucose can soar to dangerous levels while at the cellular level the body is starved of energy. This condition is referred to as hyperglycemia and it poses a risk of long-term complications.

    The goal, then, is to take the necessary steps to maintain a relatively constant blood glucose level as we eat and perform various activities throughout the day. One way that those challenged with diabetes can help avoid the spikes that can come, is to pay attention to what they eat and when they eat it. If such an individual doesn’t eat at the right time or eats too much of the wrong thing (or right thing) at the wrong time, the system can easily be thrown out of balance. In addition to proper eating and dietary habits, other natural remedies have also been widely used to help keep blood sugar levels in check. For example, Gymnema sylvestre is an herb used for centuries in India to help control blood glucose by stimulating pancreatic function.

    Numerous factors affect blood glucose levels, as well as overall health for all of us. These are of particular importance to those with pre-diabetes or diabetes. One factor that contributes to elevated blood glucose is stress. The stress hormone adrenaline increases blood glucose, releasing it into the blood to provide a needed boost of energy to meet the fight or flight needs. In a situation such as being chased by a shark, we would react physically by fighting or fleeing and that glucose would soon be used up. But what if instead we remain stationary? Many of us deal with stress on a daily basis, but we don’t deal with that stress by engaging in physical activity. Instead, we are forced to sit and deal with it. One result of that inaction can be elevated blood glucose levels.

    Cortisol is a hormone generated by the adrenal glands that can elevate blood glucose. Under conditions of high stress, cortisol provides the body with glucose by tapping into protein stored in the liver. This energy can help an individual in a fight or flight situation. However, if we’re constantly subjected to stress, the resulting chronic elevated cortisol can lead to increased blood glucose levels. To help reduce the effects of stress, we need to find ways to prevent or cope with it. Strategies include everything from exercise to nutrition, hydration, music and meditation.

    Sleep is not a luxury — it is a necessity that also has an impact on blood glucose. In fact, a chronic lack of sleep is another form of stress that can result in elevated blood glucose, according to an article in the December 2015 issue of Diabetes Therapy. The National Sleep Foundation recommends seven to nine hours of sleep every night to enjoy its restorative health effects.

    Another factor that can predispose individuals to Type 2 diabetes is a chronically low level of Vitamin D. A study reported in Scientific American in 2009, found that 45 percent of Americans are deficient in Vitamin D and more recent studies corroborate a rising trend in Vitamin D deficiencies. But here is the kicker: a Tufts-New England Medical Center study found that those who are chronically low on Vitamin D had a 46 percent increased risk of Type 2 diabetes. While the mechanism of Vitamin D with regards to diabetes is not crystal clear, researchers suspect that Vitamin D enhances the cells’ response to insulin.

    As it turns out, precautions against skin cancer may actually be depressing our levels of Vitamin D. In a 2009 Article in Scientific American, co-author Adit Ginde, an assistant professor at the University Of Colorado Denver School Of Medicine, reveals that using a sunscreen with as little as an SPF 15 reduces the skin’s Vitamin D production by 99 percent.

    As divers, we understand that hydration is a factor in decompression illness but it is also a factor when it comes to blood glucose levels. As fluid in our circulatory system is decreased due to dehydration, blood glucose becomes more concentrated. This causes an increase in urine production, which worsens the dehydration. The key message here is the importance of maintaining a healthy hydration level through consumption of water and other non-sugary beverages. Drinking water can reduce blood glucose, reduce insulin resistance and reduce hunger. If plain water isn’t enticing enough, try garnishing it with a citrus wedge, cucumber slice or fresh mint leaves.

    Exercise is a double-edged sword when it comes to those with diabetes. In general, exercise is an important ingredient in maintaining health for those with diabetes. But for those with Type 1 diabetes, some precautions are in order. Vigorous physical activity should be avoided when blood glucose level is too high (hyperglycemia) and insulin level is too low. Not surprisingly, this precaution is reflected in the diabetic diving protocols.

    While the long term effects of diabetes are daunting, the short term effects for a person with Type 1 diabetes can be downright frightening, especially if that individual should be underwater. The effects of hypoglycemia include confusion, blurred vision, impaired judgment, physical impairment, seizures and loss of consciousness. Such conditions are dangerous not only to a diver, but also the diver’s buddy. What’s more, if the symptoms aren’t recognized and properly treated, the diver could be in grave danger.

    Steve Prosterman is a Dive Safety Officer at the University of the Virgin Islands and a Hyperbaric Chamber Operator at the St. Thomas Hospital. Diagnosed with Type 1 diabetes in 1967, he became a dive instructor in 1982 and has made well over 10,000 dives with no complications. As he points out, “The main risk of diving and diabetes is the sudden loss of consciousness or altered state of consciousness due to hypoglycemia (low blood sugar). Hypoglycemia generally begins to develop symptoms when the blood sugar falls to 60-70 mg/dl and lower and can also lead to impaired judgment, physical impairment and seizures. For this reason, anyone with a history of reactions with these symptoms should not dive.”

    At first blush, we might think that diabetes is an absolute contraindication to diving due to the risk of losing consciousness underwater. But according to the Divers Alert Network (DAN), individuals with diabetes who wish to dive, can dive safely in many cases. In fact, protocols for diving with diabetes have been around for more than a decade now. The caveat is that medical screening and safety protocols must be observed.

    According to DAN, the first step for the prospective diabetic diver is to undergo the same medical fitness evaluation as other candidates to ensure no other disqualifying conditions exist. These include such conditions as epilepsy, pulmonary disease, heart disease and others. A person who has advanced diabetes and suffers from secondary complications may also be excluded.

    Next, it must be determined that no complications of diabetes exist that may increase the risk of injury while diving. DAN’s guidelines also note that candidates should be 18 years or older (≥16 years if in special training program), with a well-established treatment history and the ability to maintain blood glucose levels efficiently throughout the course of changing demands of daily activities. Those who do not have the ability to control their diabetes (read more here) can be at risk and may not be good candidates for diving. Candidates and divers with diabetes should undergo a mandatory annual medical examination and, if over age 40, should be regularly evaluated for silent cardiovascular disease.

    General precautions for diving with diabetes include limiting depth to 100 feet (30.5 m), limiting bottom time to one hour and not diving beyond the no-stop limits. It’s also recommended that diabetic divers buddy up with non-diabetic divers and that their buddy be aware of both their condition and the proper procedures to recognize and deal with a hypoglycemic episode.

    Since the primary risk comes when a diabetic diver experiences a low blood glucose condition, one key to safe diving is ensuring the blood glucose is at minimum safe level — and stable — at the beginning of a dive (see sidebar). The blood glucose must be high enough prior to starting a dive that the dive can be completed without experiencing an unsafe drop in blood glucose. Measuring blood glucose is quick and easy using one of the many blood glucose monitors available on the market today. Continuous glucose monitors (CGMs) are also available to help monitor blood glucose levels and trends.

    Good nutrition is important to everyone’s health and can help prevent the onset of such diseases as Diabetes. For those who suffer with Diabetes or pre-diabetes, staying healthy is, in part, a matter of making the right choices when it comes to dietary intake.

    Sugars and other carbohydrates are readily converted to glucose, but the rate at which that occurs is measured by something called glycemic index. A high glycemic index indicates a food will rapidly be converted to glucose, causing a rapid spike in blood sugar. A low glycemic index means that the digestive process for that food is slower, meaning a slow production of glucose and a slower rise in blood sugar. For example, white rice rapidly converts to glucose and has a glycemic index of 72, whereas an apple, which converts much more slowly, has a glycemic index of only 36. However, the glycemic load, which includes the effect of typical portion size, may be an even better measure of a particular food’s effect on blood glucose. 

    Another factor that contributes to the rise in blood sugar is the quantity of food eaten. Eating smaller portions results in lower spikes in blood sugar. For those with pre-diabetes or Type 2 diabetes, simply eating smaller portions more frequently can improve the body’s ability to maintain blood sugars in the proper range. Choosing foods with a lower glycemic index and eating healthy portions, can help keep blood glucose in the normal range.

    One area of conflicting research centers on the effects of caffeine on blood glucose. A study published in the June 2016 issue of the European Journal of Nutrition found that the risk of developing Type 2 diabetes was reduced for healthy, regular coffee drinkers consuming three to four cups of coffee per day. However, previous evidence suggests that high doses of caffeine can cause blood glucose to spike. The Mayo Clinic suggests that consuming up to 400 milligrams (mg) of caffeine (about four 8-ounce cups of coffee) is safe for most people, but it can cause trouble (spikes or lows) for those with diabetes. Limiting caffeine intake is a likely a good strategy for improved health.

    Considering the health effects of Vitamin D, all divers should strive to maintain healthy levels of this vitamin. Many foods are Vitamin D-enhanced and may have a naturally high dose of Vitamin D. These include salmon, tuna, mackerel and vitamin D-fortified dairy products. Taking Vitamin D supplements is another health-wise strategy that could help maintain pancreatic function and help control blood glucose. The advice of nutritionists is to take Vitamin D3 with a meal that contains fat, since Vitamin D is fat-soluble and this enhances uptake. Foods rich in healthy fat include fish, nuts, avocado and olive oil.

    The more we learn about human physiology, health and the effects of the underwater environment, the better prepared we are to make safe adaptations to explore the underwater world. Unfortunately, not everyone can safely enjoy scuba diving, but for many of those with diabetes, the door has been opened with safe diving protocols based on solid scientific research.

    While the criteria for diving with diabetes may vary from one certification agency to another, some of the basic criteria for safe diabetic diving include good control of blood glucose levels and freedom from severe secondary complications of diabetes. As University of the Virgin Islands Dive Safety Officer and Instructor Steve Prosterman points out, “A candidate for diving should have an understanding of the relationship between the disease and exercise, be able to recognize early and handle low blood sugars on their own and not have had a serious hypoglycemic (low blood sugar) episode within the last 12 months.”

    One way that diabetics can measure their ability to control the disease is with a hemoglobin A1C test, which provides a 90-day lookback at blood glucose levels and is a good indicator of how well blood glucose is being controlled. Most doctors will recommend that this test be performed at least twice a year. For diving, it may be suggested that the test results be within 30 percent of the normal range. Results that fall outside that range may indicate that better control of blood glucose is needed before a person undertakes underwater activities such as scuba diving.

    Also important to safety is the person’s ability to recognize the early warning signs of hypoglycemia. Divers with diabetes must have a clear insight into the relationship between diabetes and exercise and be able to recognize and respond properly when a low blood glucose situation is developing.

    Safe diving for diabetic divers requires strict protocols, as well as the development and use of good practices and habits. DAN recommends that divers make a general self-assessment of their fitness for diving on the day of the dive, as well as maintaining good hydration throughout the days of diving. Specific protocols* for glucose management on the day of diving include the following:

    §                             Before entering the water, blood glucose (BG) must be stable or rising with a value greater than or equal to 150 mg dL-1 (8.3 mmol L-1). Divers should complete a minimum of three pre-dive BG tests — performed at 60 minutes, 30 minutes and immediately prior to diving — to evaluate BG trends. It is noted that alterations in the dosage of oral hypoglycemic agents (OHA) or insulin on the evening prior or day of diving may help.

    §                             Divers should delay the dive if BG is less than 150 mg dL-1 (8.3 mmol L-1) or greater than 300 mg dL-1 (16.7 mmol L-1).

    • Divers must carry readily accessible oral glucose during all dives and have parenteral glucagon available at the surface.
    • If hypoglycemia is noticed underwater, the diver should surface (with buddy), establish positive buoyancy, ingest glucose and leave the water.
    • Check blood sugar frequently for 12-15 hours after diving to ensure safe levels.
    • In order to establish best practices for future diving, diabetic divers should log all dives and include BG test results and all information pertinent to diabetes management.
    • For more information, contact DAN and consult your physician.

    * Divers Alert Network, Guidelines for Diabetes and Recreational Diving, Proceedings Summary | DAN/UHMS Diabetes and Recreational Diving Workshop.

    Also available from DAN: Pollock NW, Uguccioni DM, Dear GdeL, eds. Diabetes and recreational diving: guidelines for the future. Proceedings of the UHMS/DAN 2005 June 19 Workshop. Durham, NC: Divers Alert Network; 2005.

    Hypoglycemia is a condition where blood glucose (blood sugar) is low. When levels fall to 60 to 70 mg/dl or less, a dangerous condition exists. Some signs and symptoms of hypoglycemia of which diabetic divers, their buddies and instructors should be aware include:

    §                             Excessive hunger

    §                             Weakness or dizziness

    §                             Confusion

    §                             Unresponsiveness or inappropriate responsiveness

    §                             Blurred vision

    §                             Glazed eyes

    §                             Sudden mood changes

    §                             Irritability

    • Loss of consciousness or altered state of consciousness
    • Seizures

    Diabetic divers who display these symptoms should follow established protocols. This includes exchanging hand signals to identify the problem, ascending and stabilizing at the surface (both the affected diver and the buddy) and ingestion of carbohydrates by the affected diver. The divers terminate the dive and return to the boat or beach where a blood test is performed. Such events, along with blood glucose results and other details of the event, should be recorded for future reference.

    The glycemic index is a measure of how rapidly a food is converted into glucose through digestion. A high glycemic index means a food converts quickly. The glycemic load is a measure of the impact of a typical portion of the food on blood glucose, taking into account the typical portion size.   Numerous online sources are available to provide values for a broad spectrum of foods.

  • June 25, 2020 11:31 AM | Howard Ratsch (Administrator)

    Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

    New Advice Cautions Against Rushed Return to Diving for Coronavirus Patients

    By Mark 'Crowley' Russell

    The Coronavirus pandemic has already had a devastating impact on the scuba diving world – but there's another question on divers' minds: 'What happens if I get it? Can I dive after COVID-19?' And the answer is not straightforward.

    An article published in the German magazine Wetnotes (click here for a Google Translated English version) on 15 April gives an insight into the medical problems that scuba divers who have contracted SARS-CoV-2 might face. In it, Dr Frank Hartig, a senior consultant and response crisis coordinator/disaster officer for SARS-CoV-2 at Innsbruck University Hospital in Austria – and a scuba diver himself – describes some of the problems he has already encountered as a physician.

    The acronym SARS – as in SARS-CoV-2, the official name of COVID-19 – stands for Severe Acute Respiratory Syndrome. SARS attacks the lungs, and while research into the long-term effects of the novel coronavirus is only just beginning, its physical impacts are all too tragically well known. Lung damage caused by conditions such as pneumonia and acute respiratory distress syndrome (ARDS) has been widely reported. It is also known to attack other organs, including the heart, although cardiac damage may go unnoticed until the heart is actually checked. Although we might not know much about the coronavirus itself, it has long been established that scuba diving with a compromised cardiopulmonary system can lead to serious injury, even death.

    In his article, Dr Hartig describes his involvement with six active scuba divers who were hospitalised with conditions brought on by SARS-CoV-2 and who subsequently recovered and were discharged. When they returned for a check-up several weeks later, they all outwardly appeared to be healthy, but a closer examination proved otherwise.

    'The first checks of these six divers, who came to the check-up clinically healthy after 5 to 6 weeks, are interesting,' writes Dr Hartig (translated from German). 'In two of them, we saw significant oxygen deficiency when under stress as a typical sign of a persistent pulmonary shunt. In two others, bronchial tubes were still very irritable during exercise, as in asthmatics. Four of the six divers in the check-up CT [scan] still had significant lung changes. None of the six divers can be released for diving for the time being, despite their wellbeing.'

    Exercise-induced asthma is a well-known contraindication to diving, and in layman's terms, a pulmonary shunt is when blood fails to pick up more oxygen as it passes through the lungs, which leads to the body being starved of oxygen. It is often caused by fluid in the lungs, also the result of pneumonia and pulmonary oedema, a condition becoming widely recognised as a leading cause of diver fatalities. 

    At this stage, any questions over long-term damage to the lungs caused by SARS-CoV-2 would be entirely speculative, but it is clear from Dr Hartig's assessment that divers who have been affected by the coronavirus should not dive until they have had a thorough medical examination – even if they otherwise appear healthy. As Dr Hartig notes, if proper precautions are not taken, 'Young, COVID-healthy people who want to dive again quickly and appear healthy at first could [slip through our fingers].'

    A report published on 12 April by the Belgian Society for Diving and Hyperbaric Medicine gives advice to scuba divers who may have contracted and recovered from Covid-19 based on current medical knowledge. To summarise, the report states that:

    1.                    Risk of Infection: Someone who has been infected with COVID-19 can still spread the virus to others. In a diving context that would be especially likely when conducting air sharing or rescue training exercises. Before returning to diving, divers should, therefore:

    ·                                      Wait a minimum of two, preferably three months, if they had symptoms of the virus 

    ·                                      Wait a minimum of one month if they tested positive for the virus but were asymptomatic.

    ·                                      Those who have not been tested and never had symptoms may still be susceptible to infection and should 'observe a waiting period' after lockdowns are lifted, which may be variable depending on location and type of diving.

    ·                                      Divers and dive centres should strictly observe guidelines for gear disinfection as distributed by DAN

    2.                    Risk of Pulmonary Barotrauma: People who have had COVID-19 may have significant damage to their lungs for an unknown period of time, possibly permanently, and therefore have an increased risk of pulmonary barotrauma – or lung overexpansion injury – even if they don't make rapid, breath-holding ascents. A diver who was hospitalised with lung-related problems should wait at least three months and undergo complete pulmonary function testing and a high-resolution CT scan of the lungs before returning to diving. Divers who had lung-related symptoms but were not hospitalised are still strongly recommended to have the test.

    3.                    Risk of Cardiac Events: Damage to the heart caused by COVID-19 may go unnoticed during the acute phase of the disease, but may lead to heart failure during diving. Therefore, it is recommended that a diver who was hospitalised with cardiac or pulmonary symptoms should, after the three-month waiting period, undergo a thorough cardiac evaluation with echocardiography and exercise testing (exercise electrocardiography – sometimes called the 'stress test'). Those who had symptoms but were not hospitalised are strongly advised to have the tests as well.

    1. Pulmonary oxygen toxicity: It appears that some COVID-19 patients' symptoms worsened after being given pure oxygen. Although little is known about an increased pulmonary sensitivity to oxygen, the report suggests it would be 'prudent' to avoid technical diving involving the prolonged breathing of hyperoxic gas with a pO2 of 1.3 ATA or higher. Simple nitrox diving (maximum pO2 of 1.4 ATA) should not present any problem.
    2. Decompression illness: tiny bubbles of inert gas form even on normal dives and are safely eliminated through the lungs during breathing. However, damage to the lungs may prevent the lungs' 'bubble filter' from working and lead to an arterial gas embolism or other form of decompression illness. Ddivers who have suffered from pulmonary symptoms of COVID-19 should, therefore, remain well within the no-decompression limits of their dives.

    Click here for the full report (available in French, Dutch and English)

    A complete assessment of the problems that divers might face following a COVID-19 / SARS-CoV-2 infection is undoubtedly many months away and, as Dr Hartig notes, any long-term medical advice will remain speculative until clinical trials have been conducted. 

    In the short-term, however, the advice is clear. SARS-CoV-2 can damage the lungs and the heart. Scuba diving with damage to any part of the cardiovascular system can lead to serious injury and death. Much as we might all wish to rush back into the water as soon as we can, doing so without proper medical consideration may cause more harm than good.


  • May 16, 2020 9:14 AM | Howard Ratsch (Administrator)

    Thanks to Robert N. Rossier  Dive Training Magazine

     Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.


     I remember from years past a particularly eager young diver who was seemingly obsessed with the desire to dive deeper. After all, he had heard that the “really good stuff” was in deep water, and that’s where he wanted to go. The misinformation he had received, combined with his desire to be seen by others as a dashing, daring conqueror of “the deep” conspired to make him a particularly “at risk” individual. Fortunately, through the efforts of a good instructor and more enlightened peers, he learned to be more cautious, and to appreciate the magical, mystical elements of the ocean realm that lay in safer depths.

    The diving world is filled with misinformation, misconceptions, misunderstandings and plain-old myths. It’s surprising that even well-educated divers and instructors can unwittingly subscribe to these untruths, and pass them on to others. After all, we were all students, and most of us took as gospel every word uttered from the lips of our instructors. What we may not have realized is that they, too, were victims of myth, misinformation, and misconceptions.

    Sometimes, especially when the information seems to make perfect sense, it’s easy to “go along” with what you’ve heard, and pass the bad data on to friends and students. In some cases, the information might be true, but the rationale is unsound. Sometimes the “myth” is partially true, or has an element of fact around which rumor and speculation have been wound. As we wade through the material required at any level of training, we must strive to separate the truth from the fiction, debunk the myths and replace them with accurate, up-to-date, verifiable information. And we need to encourage our dive buddies to do the same.

    That said, let’s take a look at some of the more common myths, and the truth surrounding those issues. Among those misconceptions are untruths and myths regarding everything from general diving safety to physiology, physics and marine life.

    Myth No.1: Diving is dangerous.

    Of course it is. If it wasn’t dangerous, nobody would need training, now would they? What’s important to understand is that while diving presents a multitude of potential hazards, it is a diver’s knowledge, training, judgment and decision making that limits or controls that risk.

    In fact, diving has an arguably good safety record. According to Divers Alert Network (DAN) Senior Research Director Petar Denoble, Ph.D., the injury rate for scuba diving is in the range of one per 2,000 participants, or an injury rate of 50 per 100,000. The Insurance Information Institute publishes injury rates substantially higher for many popular sports (2002 data), including basketball (21,300 injuries per 100,000) and golf (140 per 100,000). Diving may have an element of danger, but no more so than many other activities that are generally considered safe.

    Myth No.2: Modern scuba gear is virtually foolproof.

    There’s no question that modern scuba gear is well-engineered, well-designed, and highly reliable. That said, we still need to account for a fair number of diving accidents that occur each year that appear to be related, at least to a degree, to equipment malfunctions.

    Data on equipment problems in diving is notoriously lacking in the industry, but an Australian report on the Diving Incident Monitoring Study (DIMS) prepared a few years back for the SPUMS (South Pacific Undersea Medical Society) sheds some light on the subject. According to the DIMS data, 457 of the 1,000 reported incidents (roughly half) involved equipment, and more than 25 percent of these resulted in harm to the diver. Similarly, DAN data reveals that roughly half of the 89 fatal dive accidents in 2002 involved equipment problems.

    While such data might at first blush seem to implicate dive equipment, that perspective shifts when we dig a little deeper. In fact, the studies show that many of the equipment-related diving accidents and deaths are not “true” equipment problems. Example: Of the 52 regulator-related incidents reported in the DIMS data, only 20 were considered actual regulator malfunctions. Running out of air, panic, and other causes contributed to the remaining incidents and accidents. Similarly, while weight belts were implicated in 33 incidents out of 457 reported equipment-related incidents and accidents (7 percent), and were involved in 12 percent of the reported injuries, few of those were actually due to faulty weight belts. Many times the problems resulted from failure to drop the belt in an emergency, tangling of the belt due to improper use or placement, and other training-related issues.

    The fact of the matter remains that while our equipment may be highly reliable, it isn’t infallible. Gear is generally good, but it’s no better than the person who maintains and uses it. A diver who isn’t well-trained and prepared, or who uses poorly maintained equipment, may end up suffering the consequences. On the other hand, a diver with the proper training, knowledge, and decision-making skills who takes proper care of his equipment is less likely to suffer a problem.

    Myth No.3: The air in my cylinder is safe to breathe.

    Air is all around us, and we all know that breathing it is generally more healthy than not. We also know that the compressed air provided by a reputable dive center is usually up to par in terms of meeting the air quality requirements specified by the industry. But we live in an imperfect world, and the incidence of air contamination is perhaps higher than some would like to admit. Informal data from some of the larger independent air testing laboratories suggest that as many as 3 percent to 5 percent of all air stations tested will fail to meet the CGA Grade E standard for diver’s breathing air. As we travel to more remote destinations, the lack of good filtration equipment combined with other factors might add up to a greater likelihood of getting a “bad” air fill.

    Here again, knowledge, protocol and common sense can often help us sort out the good from the bad and the ugly. To be safe, we should buy our air from professional air stations that adhere to accepted maintenance protocols, and subject their air to periodic testing by an independent testing facility. Such results should be posted in a conspicuous location. In addition, especially if we’re using nitrox or some other breathing gas, it’s important to verify the oxygen content with a calibrated oxygen monitor.

    Myth No.4: If I use a dive computer, I won’t get decompression sickness.

    This is probably one of the most common misconceptions among divers today, but be careful how you address it. According to the latest data from DAN, between 70 percent and 75 percent of the divers injured in 2002 were using computers as their means of dive planning. “We have not indicated that dive computers should be blamed for DCS,” Denoble says. “Decompression sickness is dependent on depth-time profile in a probabilistic way: The deeper and longer you dive and faster you come up, the more likely that you will get bent. The ‘Safety Curve’ [no-decompression limits] was meant to indicate low-risk dives, but there is no guarantee that there will be no DCS within the ‘Safety Curve.’ As a matter of fact, many cases of DCS occur after so-called no-decompression dives.” This means that a very small percentage of divers will still get DCS, even if they have a properly operating dive computer, and use it correctly.

    On the other hand, we must also understand that dive computers are exactly that — computers — and as such they can readily succumb to the “garbage in equals garbage out” syndrome. While a properly functioning and correctly used dive computer is perhaps a diver’s best friend, they are not infallible, either.

    Among the many ways to put that “garbage” into our computers is to make some fairly simple mistakes, like switching computers in the middle of a dive trip (the new computer assumes you haven’t been diving yet); breathing a gas other than that for which the computer is set (air instead of nitrox, or the wrong blend of nitrox); or following inappropriate dive profiles, including “saw tooth” profiles or rapid ascents. Remember that individual physiology, use of alcohol, and challenging environmental conditions can alter the blood flow, gas diffusion, and overall absorption/desorption of nitrogen to the extent that the model used by the computer is invalid for the particular diver on the particular dive. In fact, Dr. Richard Vann of DAN says that the issue of dive computer safety has been the subject of a Project Dive Exploration study, and “the major conclusion is that the dive conditions can have significant effects on risk.”

    Myth No.5: Scuba cylinders are indestructible.

    Just look at these things. Thick steel and aluminum walls, heavy, and built for high pressure; no wonder they call them “tanks.” While a scuba cylinder may appear to be virtually indestructible, the simple truth is that they are engineered components, and sufficient mistreatment, neglect, or physical damage can render them unsafe. According to sources at Professional Scuba Inspectors (PSI) in Woodinville, Washington, cuts, dings, gouges, dents, corrosion pitting, and bulges must be compared with specific damage limits for each cylinder type. Damage or other conditions that fail to meet the allowable limits cause the cylinder to be condemned. Despite their outward appearance, cylinders aren’t indestructible, and deserve to be properly used, maintained and handled. It’s important to remember, too, that even though the cylinder itself is durable, most damage to the cylinder involves the valve, through which air flows into the first-stage regulator.

    Myth No.6: The guide/instructor/buddy will take care of me.

    It’s amazing to many of us how easily supposed well-trained divers can turn into “sea sheep,” simply following the herd without asking simple questions like, “where are we going, and how long will we stay?” All too often, divers regard dive guides as unerring, and will simply follow along. And while most of the time professional dive guides will be sufficiently conservative as to avoid decompression obligations, there are exceptions. According to the latest DAN data, 7 percent of the 348 divers injured in 2002 were relying on someone else rather than the tables or their own dive computer. What were they thinking? The take-home lesson for our students is that each of us is responsible for our own safety, and that means doing our own planning.

    Other diving myths revolve around physiology and the physics of diving. Here again, we find some common myths and misconceptions that should be cleared up.

    Myth No.7: If I feel warm, I am warm.

    Unfortunately, our ability to sense heat loss from our own bodies is not as keen as we might expect. According to the “NOAA Diving Manual,” hypothermia can even be a problem when diving in warm waters. According to this source, “A phenomenon called ‘warm water hypothermia’ can occur even in the tropics, especially during long dives and repetitive dives made without adequate rewarming between dives. In warm-water hypothermia, long, slow cooling can take place in water temperatures as warm as 91 degrees Fahrenheit (33 degrees Celsius)… The physiological mechanisms of warm-water hypothermia have been demonstrated in various medical studies, but they still are not clearly understood. The victim in this situation may not shiver, because the drop in core temperature may not be rapid enough to activate the body’s thermoregulator defense mechanism…”

    The implications here are clear: We must recognize the importance of wearing proper thermal protection, and understand that this equipment may be just as important in warm water as it is in cold.

    Myth No.8: You can’t exceed the no-decompression limits on a single tank.

    This is an old myth, stemming from the days when 72-cubic-foot (and smaller) steel cylinders were the standard of the industry, and virtually no one used a dive computer. While it may have seemed a good guideline, it wasn’t true back then, and it isn’t true today, especially when cylinders are larger, and divers go to greater depths wearing better thermal protection and consuming less air per minute.

    Myth No.9: Divers should only drink water when diving.

    Dehydration is one of the silent enemies of diving. It affects our circulatory system, and thus can alter the physics of gas transfer in the body, predisposing us to decompression sickness. While it’s true that divers should strive to maintain a high level of hydration, there’s a misconception that many of the so-called “sports drinks” are inappropriate for diving. According to Dr. Jolie Bookspan, author of “Diving Physiology in Plain English,” that simply isn’t the case. “Commercial electrolyte and carbohydrate sport drinks are not harmful to divers,” writes Bookspan. “Exercise studies are clear that sport drinks promote rehydration by helping you absorb and retain water. They stimulate your thirst mechanism to keep you drinking, and replace needed water.” According to the “NOAA Diving Manual,” divers should drink warm liquids between dives, and avoid alcohol and caffeine.

    A final category of myths revolves around marine life. In fact, there’s a whole world of myths and legends regarding the nature and habits of undersea creatures, and not all the myths are as apparent as the tales of the Loch Ness monster. Here it’s best to turn to the experts, ferret out the truth, and separate it from the fiction.

    Myth No.10: Sharks are a major threat to divers.

    I think we can blame this one on Hollywood and the popular media. There are more than 400 species of sharks, and most of them will shy away from divers. There are of course exceptions, but proper precautions can drastically limit the risk of attack by the potential “evil-doers.” While sharks can be dangerous in certain circumstances, we’re much more likely to be injured by some other means.

    Consider these facts: According to statistics from the International Shark Files project at the Florida Museum of Natural History, and the New York City Health Department, a person is roughly 600 times more likely to be bitten by a dog in New York City than by a shark when in the water. At least in the years 1981, and 1984-87, New York City documented reports of at least 8,000 cases in which a dog bit a human. The highest number of documented shark attacks nationwide in any one of those years was 14, in 1984. The number of lightning strikes offers additional perspective. Nearly as many people have been killed by lightning strikes in Florida than have been attacked by sharks, and only eight of those people have died as a result of shark attacks in Florida.

    Some of the good stuff in diving really is deep, but the myths of diving can run even deeper. Legends are fun and myths are magical, but in the context of safe diving, there’s no substitute for cold, hard facts. If we strive to verify the “facts” we hear or have learned, turning to reliable sources for verification, we can help reduce the promulgation of diving myths.


  • April 14, 2020 2:23 PM | Howard Ratsch (Administrator)

    Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.




    Buoyancy Calculator: How Much Do You Need in Dive Weights?

    Diving weights make all the difference

    By John Brumm Updated: April 15, 2019


    Pool Dive

    Pool dive weight test

    Kathy Danca Galli


    It’s the bane of all divers. We want to go down, but the inherent buoyancy in our wetsuits, our BCs, our lungs and our fat cells are all conspiring to keep that from happening.

    To overcome the force of buoyancy you have to counterbalance it with ballast weight. The question is, how much in dive weights will you need? While the answer is different for every diver, the goal is the same: carry enough weight to enable you to function efficiently and safely at all depths, and not an ounce more.

    Divers are generally taught to define this as being neutrally buoyant at 15 feet deep while wearing an empty BC and carrying a nearly empty tank. But how do you get there? There’s the basic ballpark method — carry 10 percent of your body weight in lead. Or there’s the surface float method — in full scuba gear, load enough weight to enable you to float with the water at eye level (some would say at the hairline).

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    But rather than just blindly piling on the lead, why not break it down to find out why you need to carry the weight you do, and what specifically you are counterbalancing. By deconstructing your buoyancy status, you know exactly where your counterweight needs are greatest, and that might reveal ways to reduce the amount of weight you ultimately have to carry. Here’s how:

    STEP 1: Calculate for Your Body

    How much weight do you need to make your body neutral? Take a few weights into the water wearing just a swimsuit. You will be perfectly weighted when you can hang motionless with half a breath, and sink when you exhale. (Using a snorkel can make this test easier.)

    Tip for Shaving Ballast Weight: Lose weight. Also, work to turn your fat to muscle. Fat mass is a lot more buoyant than muscle mass, so any fat you can convert to muscle will lower your buoyancy deficit.

    STEP 2: Calculate for Your Exposure Suit

    Wearing your exposure suit, get into the water and repeat the procedure outlined in Step 1. Then take the total amount of weight required to get neutral, subtract Step 1’s total, and you’ll have the net buoyancy budget for your exposure suit.

    Tip for Shaving Ballast Weight: If water conditions permit, cut down on the thickness of your wetsuit. A wetsuit can have two to three pounds of buoyancy for every millimeter of thickness. If you wear a neoprene drysuit, consider that compressed or crushed neoprene suits have much less buoyancy than standard neoprene. If you wear a fabric drysuit, remember that thinner undergarments have much less buoyancy than the puffy stuff.



    STEP 3: Calculate for Your BC

    BCs can be a huge source of inherent buoyancy, especially the older, full-featured models that have lots of traditional-style padding. It used to be common for BCs to carry upwards of four pounds-plus of inherent buoyancy, which means, of course, that you need four pounds-plus of extra lead on your weight belt to compensate for it. Fortunately, most modern BCs carry much less inherent buoyancy.

    To test your BC’s inherent buoyancy, submerge it while venting all exhaust valves to bleed air from the bladder. Knead the padding in the shoulders and backpad and behind the pockets to release air bubbles. Slowly rotate the BC to enable any trapped air to escape. Be patient, allow plenty of time for water to displace the air in the material. When you stop seeing bubbles, release the BC into the water column. If it heads to the surface you’ve got some inherent buoyancy to deal with. Add weights until the BC will hang neutrally buoyant in the water. Then count up how many weights it took to get there and you’ll have your number.

    Tip for Shaving Ballast Weight: Buy a modern BC. Models that have come onto the market within the last three or four years carry, on average, from one to 2.5 pounds of inherent buoyancy, and some carry none at all. Note: while most manufacturers don’t provide the inherent buoyancy of their BCs, you can always find that info in ScubaLab BC reviews. (

    STEP 4: Calculate for Your Tank

    The buoyancy characteristics of tanks vary widely. For example, a standard aluminum 80 is 1.6 pounds negatively buoyant when topped off, and 2.8 pounds positively buoyant at 500 psi. That’s close to a four and a half pound buoyancy differential between the beginning of a dive and the end of a dive that, of course, needs to be dealt with by adding ballast weight.

    A steel tank, on the other hand, tends to start off negatively buoyant and stay that way. For example, a high-pressure 80 is about nine pounds negative when full and three pounds negative when empty. That’s three pounds that can be removed from your weight system.

    Tip for Shaving Ballast Weight: Switch from an aluminum cylinder to a steel cylinder. A properly-weighted diver who goes from an aluminum 80 to, say, a HP steel 80 could theoretically take six pounds off his weightbelt.

    STEP 5: Calculate for Everything Else

    Gather your reg, gauges, knife, fins and any other items you regularly dive with, place them in a neutrally buoyancy mesh bag, and submerge it. The goal here is primarily to see if the total package is positively buoyant. If it is, add some weight until it becomes neutral. If it’s negative it probably won’t be by much, so consider it a ballast slush fund. It’s not working against you, and that’s all that matters.

    STEP 6: Put it All Together

    Add it all up. This should be very close to your target ballast weight requirements, and it should also give you a clear picture of where your biggest buoyancy challenges lie. To double-check your calculations, gear up with all the components you measured separately, get back into the water and repeat Step 1. If the above scenario played out like it’s supposed to, you should be floating at eye or forehead level in a relaxed position. When you exhale you should start to slowly sink. If not, you couldn’t be more than a pound or so off your target. Make the final adjustment and go diving.


    If most of your diving is done in fresh water springs or lakes, then ballast calculations should be done in fresh water. If you dive mostly in the ocean, then do the calculations in salt water. If you switch back and forth, you’ll need to adjust your ballast needs as you go. Be prepared to add anywhere from 4 to 7 pounds going from fresh to salt water.



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