Recreational Diving Fatalities & Underlying Health Issues by Dan Orr

How Risky is Diving Compared to Other Sports?

SCUBA DIVING FATALITIES are always fodder for the news media. “Woman dies after diving off Catalina Island coast,” “Scuba diver dies exploring Lake Erie Shipwreck,” “Missoula woman dies in diving accident,” . . .

It is truly unfortunate when someone is seriously injured or dies while scuba diving. It is an unimaginable tragedy, not only for the victim, but for everyone involved. It also gives the non-diving public the impression that recreational scuba diving is a dangerous sport. While there are risks involved in just about everything we do, scuba diving is not statistically more dangerous than a number of other outdoor sports.

See “How Risky Is Your Sport?” graphic below:

In 2008, Divers Alert Network (DAN) published an analysis of 947 scuba diving fatality records from the DAN Fatality Database. The fatality records were from the years 1992-2003. The results of this analysis were published by Dr. Petar Denoble in the Journal of the Undersea and Hyperbaric Medical Society (UHM 2008, Vol. 35, No.6 “Causes of Recreational Diving Fatalities”). This research identified the cascade of events that turned an ordinary recreational scuba dive into a dive with a fatal outcome. This cascade of events included: The Trigger – Harmful Action – Disabling Injury – Cause of Death. In this research, the number one triggering event, in 41% of the cases, was identified as “running out of breathing gas underwater.”

In 2015, DAN researchers analyzed another, more recent group of scuba diving fatality records. The results of this analysis, published in the 2017 DAN Annual Diving Report, demonstrated that the number one triggering event in scuba diving fatalities was now “underlying health problems.” From information published by DAN in 2017 from 2015 accident data, autopsy results were available in 29 diving-related fatalities. In 16 of those (55.2%), the cause of death was identified as an acute cardiac event. Additionally, it was stated in the 2017 DAN Annual Diving Report, “From DAN’s expert reviewers, the data indicated that a leading cause of disabling injuries was an acute cardiac event.”

One of the basic tenets of personal diver safety is the importance of maintaining good mental and physical fitness for diving and a critical component of fitness to dive is cardiac health. Cardiovascular diseases are a leading cause of death globally in the general population. Out of the nearly 18 million premature deaths annually (for those under the age of 70), nearly 40% are caused by cardiovascular diseases. Of these deaths, 85% were due to heart attack and stroke. We can reduce the likelihood of most cardiovascular diseases by considering behavioral and environmental risk factors such as tobacco use, unhealthy diet, obesity, physical inactivity, harmful use of alcohol and air pollution. It is imperative to understand the warning signs of cardiovascular disease and detect cardiovascular disease as early as possible so that management with counselling, medicines and, possibly, corrective surgical interventions can begin.

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While cardiovascular disease is of critical importance to the general population, in my opinion, it is even more critical in the diving population. This is due to the fact that divers may be in remote locations, potentially far from medical support or they are underwater in an environment that is very unforgiving when it comes to the potential for loss of consciousness. The difficulty of rescue and recovery of an unconscious diver underwater can be problematic and reduce the overall chances of survival.

Although it is disturbing that these cardiac-related fatalities occurred while participating in an otherwise safe and enjoyable sport, what is also distressing is that a significant number of those who died as a result of a cardiac event associated with scuba diving had signs and/or symptoms that could have been recognized as cardiac-related before or during the dive, but they continued to dive anyway. Had these divers or one of their diving companions simply questioned whether it was prudent to continue or “called” the dive, the fatal situation may have been averted.

With an aging active diving population (the average age of injured recreational divers being somewhere between 40 and 50), diseases associated with age are likely to be an issue. When you look at sports-related deaths, coronary artery disease is the leading cause of sudden cardiac death in those over the age of 35. The risk of cardiac-related death in divers steadily increases with age with divers older than 50 having a risk 12.9 times that of younger divers. From the DAN data, 25% of the divers who suffered a cardiac event while diving were completely asymptomatic and were totally unaware of their condition.

It is estimated that over 3 million Americans and approximately 2.8 million Europeans will scuba dive each year. While recreational diving fatalities are rare (averaging 82 worldwide) the number involving cardiac-related issues is on the increase. From 1989 to 2015, the proportion of diving fatalities involving those from the 50–59-year-old age group increased from 15% to 35%, while fatalities in the over-60s increased significantly from 5% to 20%. Cardiac events now rank the second leading cause of death in scuba divers behind drowning.

We know that diving exposes divers’ bodies to various stressors that independently affect cardiovascular function that may initiate an irregular heartbeat called an arrhythmia. These stressors include immersion, exposure to cold, and increased workload while diving. The combined effect of these factors is that the volume of blood in the vessels of the chest and heart increases significantly, stretching the walls of the heart and major vessels. While there is nothing we can do to mitigate the stressor of immersion, with some degree of forethought and preparation, we may be able to mitigate the potential for an arrhythmia by managing the other stressors. With immersion, blood pressure slightly increases, and the heart has to work harder to maintain circulation. These conditions contribute to various changes in heart rhythm (arrhythmias) that range from a slow heart rate (bradycardia) caused by cold, to fast heart rate (tachyarrhythmia) caused by the body’s response to stress. Older divers, especially those with cardiovascular disease, are at greater risk of adverse reactions to these stresses. It is vital that divers be aware of the effects of immersion on the cardiovascular system while scuba diving. There is also an increased strain on the heart due to immersion and constriction of peripheral blood vessels, an increased physical workload due to the resistance of water and the increased work of breathing through the regulator. When you add additional exertion caused by swimming against a current, wave action or simply working hard to compensate for poor buoyancy, the risk of a dive-provoked cardiac event may be significantly increased. This risk can be exacerbated by emotional stress brought on by diving in an unfamiliar location, having been away from diving for an extended period or diving beyond one’s limits.

Divers who are aware of the conditions that contribute to arrhythmias may be able to mitigate these risks associated with immersion. For example, the risks associated with exposure to cold can be mitigated by having the appropriate exposure protection whether it be wetsuits, drysuits or even diveskins. For those diving in extreme coldwater conditions, heated undergarments and heated gloves are available. For the risks associated with increased workload, divers can mitigate those risks by having a properly tuned regulator and reducing drag in the water by becoming more streamlined and improving their buoyancy control.

Besides scuba divers, snorkelers and free-divers should be aware of the potential for cardiac-related issues. Research on snorkeling and breath-hold diving fatalities in Australia, using data supplied by the Australasian Diving Safety Foundation, analyzed 317 deaths between 2000–2021. The research showed that victims are frequently older (median age 48–59), male, and often have pre-existing cardiovascular conditions, such as ischemic heart disease or left ventricular hypertrophy. Overweight or obese individuals are overrepresented, and many incidents are considered “silent” cardiac events occurring at the surface, rather than just drowning.

Also, the Hawaii Snorkel Safety Study indicates that many fatalities once thought to be from water inhalation are now believed to be caused by Rapid Onset Pulmonary Edema (ROPE), a sudden buildup of fluid in the lungs triggered by breathing resistance through a snorkel.

Maintaining general good health and having an annual physical performed by a physician familiar with diving medicine and your life priorities is perhaps the most effective way to reduce the likelihood of these types of accidents. It is important that your healthcare provider understands that scuba diving is an important component of your active lifestyle so that they take that into consideration when providing you with your fitness to dive advice. One caveat is that scuba diving should never be so important that your participation in the sport endangers yourself or those you dive with. Also, any time there is a noticeable change in your health, you should consult a healthcare professional. Regular medical evaluations are recommended for those over the age of 40 and may help identify health conditions that may need attention prior to diving. These regular health checks should also include a periodic cardiac evaluation. Once diagnosed, a physician may advise against continuing to dive or impose modified diving habits or limits. Remember, if your family physician or other healthcare professional is unfamiliar with diving, you can consult DAN for a referral to a physician familiar with diving medicine or to consult with your family physician or healthcare provider.

A word to the wise, a physician who dives may not be sufficiently familiar with diving medicine or all the medical conditions associated with scuba diving. Therefore, the Medical Department at DAN should be considered a valuable resource by your family physician. It is also important that your family physician understands your life priorities. If your physician understands that recreational diving is an important part of your lifestyle, they are less likely to simply declare that you stop diving at a certain age without fully understanding what health conditions may allow you to continue to safely enjoy diving or snorkeling.

The best way to avoid cardiac-related issues in diving and not put yourself or your diving companions at risk is to adopt a healthy lifestyle, have regular health evaluations including a periodic cardiac evaluation and always be aware of signs or symptoms of a potential medical problem. It’s far better to ‘call the dive’ or ‘call for help’ than to risk a tragic outcome. A good healthy philosophy is just as essential as any piece of life support equipment.

(Note: The above issues are covered in detail in the free webinars that are available to any group of divers at no charge. If your group is interested, please contact me at danorr@danorrconsulting.com)

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References:

Denoble, Petar, et. al., Common causes of open-circuit recreational diving fatalities. Undersea Hyperb Med. 008 Nov-Dec;35(6):393-406.

DAN Annual Diving Report – 2019 Edition. Section 1-Diivng Fatalities. Page 23

DAN Safety Stop – Cardiovascular Conditions. February 2026

Galea, Wilfred. Aging overweight scuba divers at risk of underwater heart attack. Medical News Archived, THESYNAPSE ONLINE. January 16, 2020.

Orr, D. The Ageless Diver. Divecenterbusiness.com. JULY/AUGUST 2014

Orr, D. and Douglas, E. Scuba Diving Safety. Human Underwater Kinetics. 2007.

Orr, D. and Orr, B. 101 Tips for Recreational Scuba Divers. Wise Divers Publications (www.wisedivers.com) 2022

Orr, D. Open-Circuit Diving Fatalities. Proceedings of Rebreather Forum 3. Editors Vann, R., Denoble, P., Pollock, N. 2014. pp. 103-107.

Orr, D. The Normalization of Deviance (aka “Short-Cut Mentality”). DiveNewsWire.com. March 16, 2021.

Orr, D. Time to Return to Diving – But Cautiously. DiveNewsWire.com. March 29, 2021

Strauss, Michael B., Scuba Diving in Older Adults. Best Publishing WCHM. 2013. pp. 27-37.

Strauss, Michael B. Orr, Dan, et al, Diving Science . . . Revisited. Best Publishing WCHM. 2022.

World Health Organization (WHO). Health Topics: Cardiovascular Diseases.

Ziegler, J. (2002). Recreating retirement: How will baby boomers reshape leisure in their 60s? Parks and Recreation, October, pp. 56-61.

What Dive Businesses Should Do About Underlying Health Risks

Cardiac-related incidents are now a leading trigger in recreational diving fatalities. Here’s how dive retailers, instructors, and operators can reduce risk while strengthening professionalism and trust.

1. Reinforce Medical Screening Protocols

Ensure all divers complete updated medical questionnaires and follow referral requirements when indicated. Do not shortcut screening for returning or long-time customers.

2. Promote Annual Fitness-to-Dive Evaluations

Encourage divers over 40 to seek regular medical evaluations, including cardiac assessments. Position this as responsible diving, not restrictive diving.

3. Normalize “Call the Dive” Culture

Create an environment where divers feel comfortable aborting a dive without embarrassment. Safety-first culture builds long-term loyalty.

4. Reduce Physical Stressors on Dives

Plan dive profiles that minimize extreme exertion, strong currents, unnecessary overexertion, and poor buoyancy challenges — especially for older divers.

5. Emphasize Proper Equipment Maintenance

Ensure regulators are tuned, exposure protection is appropriate, and equipment setup reduces workload and drag.

6. Provide Clear Briefings on Exertion and Warning Signs

Include reminders about recognizing symptoms of cardiac distress, fatigue, or breathing difficulty. Encourage divers to communicate early.

7. Protect Your Business Through Proactive Risk Management

Strong safety culture reduces incidents, protects reputation, and strengthens insurance positioning. Prevention is both a moral and business imperative.

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