More Than Just Bubbles

Diving grants a freedom to explore and an opportunity to experience what most people see only on film. As terrestrial creatures, we are ill adapted to the marine world but nonetheless eager to survey the ocean’s wonders. For divers new to the sport as well as seasoned veterans, each dive is unique and requires diligent preparation prior to entering the water. Divers recognize that any excursion into or under the water carries with it some risk of injury.

In numerous articles, seminars and presentations, DAN® proclaims the benefits of physical and mental preparation prior to diving, which include physical fitness, equipment maintenance and skills training. Well represented throughout DAN’s publications and research and integral to the dive industry’s introductory training programs is a focus on decompression sickness (DCS).

The emphasis on DCS indicates the relative importance of this unique malady and the behaviors we can employ to prevent it. Often missing from discussions about DCS, however, is acknowledgement of its relative rarity and the comparative commonality of other injuries that can occur while diving or while on a diving trip.

What Harms Divers?

Female diver looks like she's choking on bubbles

DAN has been gathering dive injury and fatality statistics for more than 30 years. In 2008 a team of researchers led by Dr. Petar Denoble, senior director of DAN Research, published a paper on the causes underlying dive fatalities. While the ultimate endpoint of incapacitating events is often classified as drowning, the triggering events that lead to these deaths provide insight into how such accidents can be avoided. Whether from health-related problems such as heart disease, which accounts for approximately 26 percent of dive fatalities, or other triggering events like running out of gas (41 percent), entrapment (20 percent) or trouble with equipment (15 percent), the majority of dive fatalities stem from human factors.1 This is a recurring theme throughout the published literature on accidents and mishaps in other fields such as medicine and aviation, and it points to the importance of procedures, consistent practices and a disciplined focus on accident avoidance.

Running out of gas, entrapment and equipment problems — three human-related triggers — account for about 75 percent of dive fatalities. The common pathway toward in-water debilitation in most of these cases was asphyxia or rapid ascent associated with pulmonary barotrauma (lung-overexpansion injury) and subsequent arterial gas embolism (AGE). In the unforgiving marine environment, debilitation or unconsciousness usually results in drowning.
It is important to stress the significance of AGE in the fatality statistics and differentiate it from DCS. AGE is far more likely to lead to drowning, as symptoms often occur while the diver is still in the water, the onset is sudden, and they often result in loss of consciousness.

DCS in Perspective

Divers spend a great deal of time and money on DCS prevention; all such efforts are laudable and contribute to the low incidence rates that we see in recreational diving (aggregated DCS incidence from all sources is 2 to 4 cases per 10,000 dives).2 In addition, DCS is rarely fatal and, at least among recreational divers, an uncommon cause of long-term disability.

Although severe symptoms, long-term disability and death are rarely associated with DCS, this is by no means an endorsement of unsafe decompression practices or encouragement to slacken preventive efforts. In fact, conservative training standards, adherence to established protocols and diligent monitoring of nitrogen exposure are essential contributors to the relatively low likelihood and consequences of DCS.

The point is that divers must not ignore other aspects of their diving activities, no matter how mundane they seem. We must, for example, ensure adequate air supplies and properly configured equipment. On a statistical basis, errors and omissions in these areas have much greater lethal potential than DCS.

Shifting the Focus

Decompression-related problems represent only a fraction of the injuries and medical problems that traveling divers experience. Dive trips often involve other forms of recreational activities and thus, additional sources of injury. Of the calls DAN receives from symptomatic individuals who receive evacuation or medical-care-coordination, about 70 percent have injuries that are not related to diving. This is a powerful statistic that points to other causative factors. Trauma tops the list as the single most common injury type about which DAN receives calls for assistance. From broken legs to car accidents, our evacuation services spend the most time on injuries acquired out of the water.

Whether cycling, driving, walking or riding a scooter, the risk of injury while out of the water warrants enhanced attention. If you’re a diver who wears multiple computers to ensure adequate DCS prevention, don’t put all your safety eggs in that basket and forget to watch your footing on boat ladders. Increase your caution while traveling in areas that have different traffic patterns than those with which you are familiar. A focus on injury prevention is of maximal importance in remote locations; the quality of medical services is not equivalent around the world, and transportation and evacuation to higher levels of medical care may take more time and involve more complications than you anticipate.

Accidents are by definition unplanned. Our best defense against them is education, which enhances our knowledge of possible hazards and guides behaviors that reduce their likelihood. First aid and rescue diver courses are prime examples of programs that don’t just teach people what to do when accidents happen, they promote heightened awareness and a mindset of prevention.

Live safely, dive safely, and may all your dives and travels be accident- and injury-free.


  1. Denoble PJ, Caruso JL, Dear GL, Pieper CF, Vann RD. Common causes of open-circuit recreational diving fatalities.UHM 2008, Vol. 35, No. 6.
  2. Vann RD, Freiberger JJ, Caruso JL, Denoble PJ, Pollock NW, Uguccioni DM, Dovenbarger JA, Nord DA. Annual Diving Report. Divers Alert Network: Durham, NC, 2006; 99pp.

© Alert Diver — Q2 Spring 2013