What the diving accident data shows, and where it comes from.

Where the numbers come from

Divers Alert Network (DAN) runs a fatality surveillance programme. DAN says its purpose is to track trends and find risk factors so that diving can be made safer. The work is older than DAN's part in it: DAN credits John McAniff of the National Underwater Accident Data Center at the University of Rhode Island with starting to collect US recreational diving fatality data in 1970. DAN joined him in 1989 and worked alongside him until he retired in 1995.

DAN's surveillance page says the programme looks mainly at scuba deaths in the United States and Canada and leaves out commercial diving, although its reporting form also takes freediving cases. Cases reach DAN through news and internet monitoring, reports sent in by witnesses and dive operators, and follow-up with families and investigating agencies. Each case is stripped of identifying details and reviewed by DAN researchers and physicians. DAN publishes the results in its Annual Diving Report, free in the DAN Publication Library, and longer analyses in journals and at conferences.

A 2025 InDepth article by DAN research associate Cat Harris (5 March 2025) describes a wider net today. It says DAN now tracks deaths worldwide across snorkelling, freediving, recreational, technical, commercial, public-safety, cave, rebreather and scientific diving, and collects non-fatal incidents and near misses through its Diving Incident Reporting System. Evidence can include police and medical-examiner records, witness accounts, dive computer profiles, equipment inspections, gas analysis, autopsy and toxicology reports, and medical and training records. The article says a case file can take up to two years to complete, and that DAN looks past a recorded cause of drowning for the root cause and the event that set it off. The same article puts worldwide diving deaths at close to 300 a year; we found no second source for that figure, so it could not be confirmed.

The latest DAN report we could confirm

DAN announced on 15 November 2022, after a delayed release, that the 2020 edition of its Annual Diving Report was available. That edition covers incidents from 2018. It looked at breath-hold incidents, injury monitoring, where incidents happened, equipment failures, the role of training, and divers' heart health and fitness. Our research could not confirm any later edition, so this page has no DAN fatality counts for 2019 or after.

A DAN Europe Alert Diver article by Claudio Di Manao (8 July 2024), drawing on the 2020 edition, gives this breakdown of 189 diving-related deaths worldwide in 2018:

The article says drowning was usually the immediate cause of death but heart problems were the leading underlying cause, with associated conditions including high blood pressure, hardened arteries, an enlarged heart, asthma, obesity and drug use. It names divers aged 50 to 59 as the highest-risk group in the 2018 data and says incidents among US and Canadian divers fell markedly against the previous ten-year average. The author adds that it is still an open question whether older divers have more accidents or whether the diving population is simply getting older.

The four-step analysis: Denoble and colleagues, 2008

A detailed breakdown comes from Denoble, Caruso, Dear, Pieper and Vann, published in Undersea and Hyperbaric Medicine in 2008. They reviewed 947 recreational open-circuit scuba deaths from 1992 to 2003 and, where the data allowed, traced each through four steps: the trigger, the disabling agent, the disabling injury and the cause of death.

The study linked cardiac incidents with existing heart and circulatory disease (odds ratio 10.5) and with age over 40 (odds ratio 5.9). The authors argued that the disabling injury tells you more than the recorded cause, because drowning often followed an injury that had already incapacitated the diver.

A DAN Alert Diver article by Nicholas Bird, MD (Spring 2013) summarised the study as showing that most deaths begin with human factors, with running out of gas, entrapment and equipment trouble together making up about three quarters of triggers. Bird wrote that arterial gas embolism is far more likely than decompression sickness to end in drowning, and described decompression sickness as rarely fatal among recreational divers. He also reported that about 70 percent of symptomatic callers to DAN who needed evacuation or care coordination had injuries unrelated to diving, such as falls on boat ladders, cycling or driving accidents.

Breaches of safe practice: Shreeves and colleagues, 2018

Shreeves, Buzzacott, Hornsby and Caney (International Maritime Health, 2018) studied 119 incidents in which 122 recreational divers died in North America and the Caribbean, none of them on training dives. They found:

• 57 percent of deaths were associated with a medical event and 43 percent were not.
• Breaches of accepted safe practice appeared in 45 percent of deaths overall: 23 percent of medical deaths and 75 percent of non-medical deaths.
• Non-medical deaths were about seven times as likely to involve a breach (odds ratio 7.3).
• The odds of a non-medical death rose about 60 percent for each extra 10 metres of depth, and the odds of a medical death rose about 9 percent for each year of age.

The authors' own recommendations were physical fitness, regular medical check-ups, especially with age, and following established safe diving practice.

How big a share is cardiac? The sources measure it differently

• Denoble et al. (2008): cardiac incidents were 26 percent of disabling injuries but 13 percent of recorded causes of death.
• DAN's page on cardiovascular fitness by LCDR James Caruso, MD (undated): cardiovascular events cause 20 to 30 percent of diving deaths.
• DAN Europe's 2024 summary of the 2018 data: heart problems were the leading underlying cause.
• Wikipedia (secondary): about a quarter of diving deaths are associated with cardiac events, mostly in older divers.

These figures count different things over different years, so they should not be read as contradicting one another or combined into one number.

The UK picture: BSAC's 2024 report

BSAC published its Diving Incident Report for 2024 on 12 November 2025. It was compiled by BSAC Incident Advisor Jim Watson and data analyst Ben Peddie and covers divers trained by any agency. It recorded 12 UK diving deaths and 239 UK incidents. BSAC's page also gives 331 incidents in total; Divernet's report of 2 November 2025 explains the difference as 239 in the UK plus 92 overseas.

Divernet reports that the 12 who died had an average age of 57.4, and that half were diving alone or had become separated from their buddy. It says decompression illness cases kept falling, with fewer linked to dives deeper than 30 metres, fast ascents or missed stops, while repeat diving was the growing factor. BSAC recorded seven medically confirmed cases of immersion pulmonary oedema and one possible case, none fatal. BSAC says that experience and qualifications do not necessarily stop someone becoming a casualty, and it invites confidential incident reports from divers of any agency, in the UK or abroad.

More studies DAN lists

DAN's surveillance page lists further peer-reviewed fatality studies: Buzzacott and Denoble (2017) on possible oxygen toxicity seizures from 2004 to 2013, Caruso et al. (2003) on buddy versus solo diving, Denoble et al. (2006) on divers with diabetes, Potts et al. (2016) on thirty years of American cave diving deaths, and Rowley et al. (2016) comparing divers who harvest seafood with those who do not. For how these findings relate to illnesses, see decompression sickness and barotrauma and fitness to dive. For how many people dive in the first place, see how many people dive.