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Denoble PJ, editor. DAN Annual Diving Report 2019 Edition: A report on 2017 diving fatalities, injuries, and incidents [Internet]. Durham (NC): Divers Alert Network; 2019.
The 2019 DAN Annual Diving Report presents descriptive statistics and selected case summaries of recreational diving fatalities collected in 2017. We are also showing a comparison with the last ten years where possible. The most notable trend in 2017 data is the increase in the average age of victims. The age in itself is not a direct risk for diving, but it may affect health and physical fitness in a way that diving becomes risky. Still, for most people, recreational scuba diving may be safe if practiced responsibly, and if we could identify those who may be at an increased risk of dying while diving. (Note that Section One covers fatalities associated with scuba diving while Section Four covers injuries and fatalities associated with breath-hold diving.)
The data collection process has not changed since 2016. It begins with an initial notification that may come as voluntary reports from affiliated organizations and individuals, active internet search, and automated internet alerts.
Online news media outlets are monitored for keywords involving breath-hold diving and scuba deaths. Sorting through the media alerts is especially tedious work. Regardless of how refined the criteria are, the by-catch of redundant and useless reports far exceeds the number of unique accident cases. Other sources of notifications regarding fatalities include families of DAN members and friends and acquaintances of decedents who are aware of DAN’s fatality data collection efforts. The DAN Medical Services Call Center (MSCC) is the most valuable single resource since the DAN Medical Services Department assists with the management of any diving incident that is called in, whether or not the victim is a DAN member.
Each death is classified as to whether or not it should be followed up on. All recreational diving fatalities that occur in the U.S. or Canada and all deaths of U.S. or Canadian citizens, no matter where they occur, are marked for follow-up. Any fatalities that occur outside the U.S. or Canada and involve citizens of other countries are classified as foreign and are not followed-up on due to logistic issues. Cases that occur during non-recreational dives (e.g., military dives) are classed as non-recreational, and they are not followed up on either. Breath-hold fatalities are classified as a distinctive group, and the follow up is attempted when the contact information is available.
DAN does not conduct investigations of diving fatalities. However, local law enforcement agencies or the U.S. Coast Guard (USCG) frequently investigate diving-related deaths in the U.S. A proportion of victims are subject to autopsies. Sometimes it takes over a year to complete the investigation and produce the reports. DAN tries to obtain all available reports, but there are often administrative hurdles to overcome. In many cases, these reports could not be collected, which impedes our ability to conduct analysis.
DAN uses its Fatality Reporting Form to collect fatality data from witnesses and family members. The form may be downloaded from the DAN website (https://www.diversalertnetwork.org/files/DivingFatalityReportingForm.pdf) or requested from the DAN Research or Medical Services departments. When necessary, a family member of the decedent may be contacted to assist in the data-collection process. Family members may complete the Fatality Reporting Form and/or provide authorization for the release of the decedent’s autopsy report. The incident reporting form on the DAN website (https://www.diversalertnetwork.org/research/incidentReport/) can also be used by family members and witnesses to report diving fatalities or to provide additional details regarding already reported fatalities.
DAN Research maintains the diving fatality data on a secure server. Once all pertinent information has been gathered and entered into the database, the results are analyzed and published in the DAN Annual Diving Report.
Worldwide, DAN received notification of 228 deaths involving underwater diving during 2017. A breakdown of this total is shown in Table 1-1.
Number of collected fatalities worldwide (n=228).
Only 162 pertained to recreational scuba divers, 70 of which occurred in the U.S. or Canada or involved U.S. or Canadian citizens (follow-up cases) and thus were actively investigated by DAN. DAN also received word of 9 scuba-related fatalities that did not involve recreational divers and 57 fatalities associated with breath-hold diving. The total numbers of received notification and follow-up cases for 2007 to 2017 by year are shown in Figure 1-1 along with the data for the same periods average.
Total number of reports collected and the number of follow up reports in 2007-2017.
Autopsies were available for 20 of the 70 U.S. and Canadian cases (30%) and nine of the 57 breath-hold cases (10%).
The number of fatalities by country of death for 2017 is shown in Table 1-2.
The number of fatalities by country of death in 2017.
Table 1-2 does not necessarily reflect the true numbers of cases worldwide. Rather, it reflects the DAN data collection process, which is focused on the scuba death of U.S. and Canadian citizens worldwide and all deaths in the U.S., Canada, Mexico, Caribbean. The country with the largest number of recreational scuba diver deaths in our dataset is the United States of America (42) followed by South Africa (9), Australia, Canada, and Pacifica (8 each), Scotland and Italy (7), UK and Mexico (6). The total number of recreational scuba deaths for the ten years is shown in Table 1-3. For numbers of fatality among DAN Europe members, see page 92.
The 10-year total number of scuba fatalities by country.
Number of follow-up cases by state/province for 2017.
The state that consistently reports the largest number of scuba deaths is Florida with 14 and 205 cases in 2017 and preceding 10 years, respectively. California follows on this list with 6 and 110 cases in the same time frames. See Figure 1-2.
Total number of cases in California and Florida in 2017 and the preceding 10 years.
While we do not know the numbers of dives by states, Florida and California are the two most popular dive destinations. We looked at the number of fatalities by county in Florida and California. The results are shown in Figure 1-3 for Florida and Figure 1-4 for California.
Florida fatalities by county 2017 and the preceding 10 years.
California fatalities by county in 2017 and the preceding 10 years.
The Number of scuba deaths in Monroe County, Florida (74 for the ten years and 6 for 2017), far exceeds Palm Beach (25 cases) and Broward (20 cases) counties in the ten years. The Monroe county includes attractions like wrecks of USS Oriskany, Spiegel Grove and USAFS General Hoyt S. Vandenberg.
In California, the county with the largest number of scuba fatalities in Los Angeles county with 44 in ten years and three in 2017. The second largest is Monterey, with 24 and San Diego with 14 in ten years.1
Figure 1-5 shows the distribution by age and sex of the 67 cases for which that information is known. In 79% of the 70 cases, the victims were male (n=55), and in 21% of cases, the victims were female (n=15). The age of the victim was unknown in three cases. More than two-thirds of the 67 victims whose age is known (66%) were 50 years of age or older, and more than four-fifth (80%) were 40 years or older.
Age and sex distribution.
The victim’s medical history was, in most cases, incomplete or unknown.
Information about decedents’ diving certification level was missing in most cases. Decedents’ years of diving experience since their initial certification was known in only four cases.
Figure 1-6 shows the type of diving activity undertaken during the fatal dive. Information was available for 48 of the 70 cases (69%). At least 35 cases (50%) involved leisure or sightseeing, 7 (10%) involved spearfishing, hunting, or collecting game, 3 (9%) were training dives, one instructing, and one photographing.
Diving activity during the fatal dive (n=48).
For examples, see cases 1-2, 1-4, 1-5, 1-14, 1-15, and 1-24 in the Fatality Case Summaries section, page 25.
The dive platforms from which fatal dives began was reported in 55 cases (76%). In 32 of those 55 cases, the dive began from a vessel, and in 23 cases, it began from shore. See Figure 1-7.
Dive platform during the fatal dive (n=55).
Environment: The majority of fatal dives occurred in an ocean/sea environment (n=50, 71%), with the rest occurring in freshwater (n=12, 17%, two of which in a cave) or in rivers or springs (n=4, 6%). In one case, a description of the environment was missing. See Figure 1-8.
Dive environment during the fatal dive (n=50).
For examples, see cases 1-7, 1-10, 1-16, and 1-17 in Fatality Case Summaries section on page 25.
Visibility: Only 5 cases (7%) included information on visibility, this serves as an example of the challenges of gathering complete data on diving fatalities.
A similar lack of data is seen with sea conditions, current, protective suits, breathing apparatus (4 used a rebreather), breathing gas, and the dive profile details.
Buddy status: At least two dives were intended as solo dives. For most dives, the buddy status at the beginning was not known. Of those who started with a buddy, six ended up separated, but there is no evidence that it was intentional. In some cases, the disappearance of the victim was not noticed immediately, and in other victims left the group and did a rapid ascent to the surface. In several cases, buddies stayed with the victim for the entirety of the dive, brought the victim to the surface, or accompanies them during the emergency ascent, but the outcome still was fatal.
We use the following dive-phase categories: a) on the surface before diving, b) underwater, c) on the surface after diving, and d) exiting the water. Dive-phase information was available in 48 of the 70 cases (66%).
Figure 1-9 shows the distribution of this information. In the majority of the 48 cases where the information was known, the diver lost consciousness underwater at the bottom (n=21), or on the surface following the dive (n=12), out of the water (n=6), during descent early in dive (n=4), during ascent (n=4), or at the surface before the dive (n=1).
Phase of dive when diver lost consciousness (n=48).
It appears that the problem that led to fatality became critical underwater in 41 cases and seven at the surface. For the remainder of the cases, it was not possible to establish.
The available data limit the analysis of the causes of injuries and deaths. The most reliable source in this dataset was the autopsy report, which was available in 20 scuba and 9 breath-hold cases. While the pre-existing cardiac conditions were often present, direct causality was difficult to establish. However, it is of note to report that in 7 autopsies, significant cardiomegaly was found.
The cause of death, as established by the medical examiner, is shown in Table 1-5.
Cause of death by medical examiner.
The most common cause of death (COD) was drowning, which is expected as any condition that disables a diver while in the water may result in drowning. Heart disease or acute cardiac events were established in five cases. It appears that medical examiners assigned heart disease as the cause of death based on significant pathological substrates found, known as the history of heart disease and sometimes the description of the course of events. The pathological substrates included cardiomegaly, LVH, pulmonary edema, extensive CAD, and pacemaker. For details, see cases 2, 6, 7, and 8 in Fatality Case Summaries. Arterial gas embolism (AGE) was a circumstantial diagnosis without a specific pathological substrate. The case of the death due to DCS occurred in a 70-year-old diver after diving to 122 msw (400 fsw) and omitted most of the decompression.
The most common disabling injury that rendered the victim incapable of using protective equipment underwater or of reaching surface alive was an acute heart disfunction in all five cases with the cause of death attributed to heart disease. Besides, there were four cases with drowning as the causes of death, where the disabling factor was an acute heart event. See cases 1, 3, and 5.
Disabling injury.
Disabling agents or mechanisms of injury are shown in Table 1-7. The disease was the most likely disabling agent in ten cases, nine of which pertain to disabling heart conditions and one to the upper gastrointestinal bleeding. In three cases, the injury was caused by rapid ascent while holding breath, in three cases it was unknown, and omitted decompression, out-of-gas, uncontrolled sinking, and saltwater aspiration were suspected in one case each.
Diabling agent.
Triggers that initiated a chain of events leading to fatality, as shown in Table 1-8, were not identified in most cases.
Triggers.
Most cardiac-related accidents occurred apparently without any obvious external cause. In a few cases, the cardiac-related death was associated with exertion caused by negative buoyancy. The entanglement and equipment problem was the trigger for two other fatalities. In one case, the panic, which usually needs a trigger, was considered the trigger itself. It occurred in a student on his first dive, without an obvious cause.
In 2017, among the 29 cases where autopsy was available (20 scuba and 9 breath-hold), in ten scuba cases and six breath-hold cases, the cause of death or disabling condition was an acute cardiac event. There were often multiple pre-existing conditions among the victims. While the presence of any of those conditions alone may not be critical, when presenting together, they should be judged as disqualifying for diving in retrospect.
Fatality Case Summaries 1-1 through 1-4 (Page 25) have multiple health conditions and risk factors that increase the probability of premature death due to cardiovascular disease in common. Cardiovascular diseases (CVD), including stroke and heart attack, are the most common causes of death. According to the CDC National Vital Statistics Report for 2017, among the general population of the USA, heart attack causes one out of four deaths while stroke causes one out of 20 deaths.1,2 The annual incidence of heart attack is 805,000 and of stroke is 795,000.3,4 Thus, it is not unexpected that some CVD related deaths occur in scuba divers while diving. Both heart attack and stroke are disabling conditions which, in scuba diving may be lethal more often than in other conditions since it occurs underwater and may involve considerable delay to immediate CPR. In 2017, among 25 cases with available autopsy, there were nine cases with probable cardiac causes and no cases with suspected stroke.
Sudden cardiac death (SCD) may be caused by an acute blockage of heart arteries (myocardial infarction), undiagnosed coronary heart disease, enlarged heart (cardiomyopathy), or thickened walls of the left ventricle (left ventricular hypertrophy, LVH), valvular heart disease, heart failure, and arrhythmias. Known risk factors for SCD are the same as risk factors for coronary artery disease: a family history of coronary artery disease, smoking, high blood pressure, high blood cholesterol, obesity, diabetes, and a sedentary lifestyle. Among other factors that increase risk are age, being male, use of cocaine or amphetamines, low potassium or magnesium levels, obstructive sleep apnea, and chronic kidney disease. Stress and strenuous exercise to which subject is not accustomed may precipitate the SCD in people with pre-existing conditions as reported for skiers and mountaineers.5
The prevalence of CVD conditions among scuba divers is not known. Surveys show that many divers continue diving after being diagnosed with heart disease or arrhythmias.6,7 Indeed, not all heart conditions are necessarily contraindications for diving, which is considered a leisurely activity. However, sometimes diving may be strenuous, and thus, when multiple risks or heart conditions are present, medical fitness for diving should be scrutinized.
It is of note that two-thirds of the reported fatalities in 2017 were between 50 and 80 years of age. Out of 30 witnessed fatalities, 15 fit the description of SCD, and in ten out of 20 with an available autopsy, SCD was found to be the probable cause of the scuba fatality. Some form of heart disease was present in many cases, but in the four described in the Fatality Case Summaries (Cases 1-1 to 1-4), multiple conditions were present: hypertensive heart disease, cardiomegaly, diabetes, obesity, in addition to advanced age and other risk factors like smoking.
Cardiomegaly was often found in this small case series. The causes of cardiomegaly are many like hypertension and others that increase with age. During the early stages, subjects are asymptomatic and tolerate exercise. Others are asymptomatic at rest but experience shortness of breath with exercise. Even in asymptomatic subjects, cardiomegaly increases the risks of arrhythmias and SCD. The prevalence of asymptomatic cardiomegaly is not known. An indication of what it could be is the prevalence of symptomatic heart failure (HF) in the USA, which is about 6 million.3 While people with HF are not likely to dive, it is important to screen for asymptomatic cardiomegaly in divers with risk factors.
We had no information if these victims underwent a medical evaluation before diving, whether the examination was thorough, and what advice they have received, but one link in this chain failed. Let us be reminded:
Atrial Fibrillation (AF) is characterized by irregular electric impulses coming from aberrant sites in the left atrium and may decrease heart output. Some people get AF from time to time and, after a brief episode, revert spontaneously or under medication back to a normal rhythm. Some people must take medication all the time to maintain a normal rhythm. An alternative to medication is to treat AF with ablation, a type of surgery that removes sources of irregular electric activity, like in Case 1-7. However, some people are permanently in atrial fibrillation, like Case 1-8, and they usually receive chronic medication to keep their heart rate under control. While the participation of people with periodic AF may be disputable, in the case of permanent AF, under the current guidelines for fitness to dive evaluation, the diver should be considered unfit. Return to diving after ablation should be discussed with a cardiologist. Even after cardiology consultation, the risk of sudden debilitating arrhythmia is always looming above patients with AF. Thus, if a diver with AF decides to continue diving, he should carefully choose his diving opportunities and should disclose his condition to his buddy and dive operator. They should strictly adhere to safe buddy diving practices, including always returning to the surface together.
Buddy diving is a potentially life-saving practice for scuba divers. Properly implemented, it helps to prevent accidents and to avert bad outcomes of possible incidents. Buddy diving starts with sharing the dive plan, getting familiar with each other’s equipment, pre-dive buddy check, keeping an eye on each other during the dive, sticking to the plan, returning to the surface together, and conducting a post-dive debrief. Every year, we see many cases illustrating the failure of a buddy system, as well as cases where the buddy system could not help despite the proper conduct of both partners (Cases 1-9, 1-10, 1-11).
Buddy assistance is probably most valuable when one buddy suddenly has issues with a gas supply, but it may help in other situations too. For the buddy assistance to be of value, buddies should stay close to each other and check each other often. The classic buddy system means two divers diving together dedicated to each other’s safety. In a group of three or more divers, it is unlikely to expect the same level of dedication and attention to the needs of others.
In real life, buddies often separate but this is rarely intentional. Without strong discipline, it is easy to lose sight of a buddy. It seems that the separation has become common and that buddies rarely abort their dive and go to the surface to wait there to re-establish contact. Even without separation, one diver may become unconscious and sink to the bottom without his preoccupied buddy noticing it. Thus, it is wrong to assume that an out-of-sight buddy has intentionally separated and to continue to dive without attempting to find him.
In guided diving, there is often one diver in the lead and one following the group with the task to herd all divers together. Despite this attempt, divers often get lost or drown unnoticed. Maybe it would help if each diver in a group had an assigned buddy.
In some cases, the affected divers alert the buddies of their intention to surface. Their distress may not always be obvious to their buddy, and they may not have time for explanations. Since their buddy did not comprehend the problem, the distressed diver’s main priority is to reach the surface. For buddy diving, the rule is for both divers to return to the surface at the same time. It is even more important to follow this rule when one buddy decides to ascend sooner than originally planned. A special situation is in case the instructor has two or more students, and one gets in distress. Taking just one student to the surface may be fatal for the inexperienced diver left at depth.
As a final note, Case 1-11 should be a warning to experienced divers who may feel that the buddy system is only for novice divers.
There remains a lot to learn about why divers separate, what is the best and most efficient practice of buddy diving, how to monitor divers in the group, and how to make the buddy system more reliable in general.
This is a 60-year-old male scuba diver with a significant history of hypertension, morbid obesity (BMI = 37 kg/m2), known coronary artery disease, diabetes, who was diving under ideal conditions in shallow water checking out his gear. He had trouble descending, so he added extra weights. He silently disappeared from his buddy, and nobody witnessed his last moments. A swimmer passing by found his body and required assistance to bring him to the surface. EMS happened to be nearby and they administered CPR/ACLS (advanced cardiovascular life support) without success.
The autopsy findings, based on the coroner’s summary, did not provide an explicit cause of death, but the major findings included critical coronary atherosclerosis, cardiomegaly (heart weight = 600 grams) with left ventricular hypertrophy. The final cause of death was drowning, but there was no evidence to establish the disabling condition that rendered him unable to protect his airways underwater. The fluid in his sinuses may indicate that he was already unconscious and not able to equalize pressure while sinking to the bottom.
Based on the autopsy findings, lack of fitness, his struggle with buoyancy, and silent disappearance, it is quite likely that he developed a dysrhythmia and cardiac arrest.
A 57-year-old male [180 centimeters (71 inches), 102 kilograms (224 lbs), BMI = 31.2 kg/ m2] had a known hypertensive heart disease and an implanted pacemaker rated for 10 msw (33 fsw). His physician advised no diving deeper than 6-8 msw (20-25 fsw). Shortly after diving to 12 msw (40 fsw), he began experiencing trouble and came to the surface where he lost consciousness. He was brought to the boat, and CPR was promptly started without success.
The autopsy report lists an abnormally enlarged heart (cardiomegaly; heart weight = 600 grams), enlarged liver and spleen (hepatosplenomegaly), severe damage of the kidney (bilateral arteriolo-nephrosclerosis), and an implanted pacemaker.
This diver had a history of hypertension and troubling arrhythmia that required an implanted defibrillator. In such cases, the fitness to dive could not be judged solely on whether the implanted pacemaker would withstand the pressure but also the indication. Screening for cardiomegaly should be considered, and tests like chest x-ray, electrocardiogram (ECG), or echocardiography should be used.
The ability of the implanted device to withstand the ambient pressure for the depth of the dive site is paramount to the device’s successful operation. An implantable pacemaker rated for 10 msw (33 fsw) is not suitable for diving. However, even with a pacemaker rated for greater depth, patients who need it require greater scrutiny, including a physical exam, specialty consultation and reviewed with a diving medical physician. Any depth limitations must be conveyed to the patient and his dive partners. The dive operator must fully understand the restrictions and be able to safely accommodate such a diver.
The diver is a 50-year-old, morbidly obese (BMI = 36.2 kg/m2) male, who was a smoker with a history of hypertension indicated that he was experiencing difficulty breathing (or chest discomfort) toward the end of his planned dive. Other divers proceeded to the surface to assist him, but before reaching the surface, they observed that he suddenly stopped his controlled ascent (he probably became unconscious at that point) and sunk to the bottom without struggle. He never dropped his weight belt. He was retrieved and brought back to the boat, where resuscitative efforts were unsuccessful.
Autopsy revealed pulmonary edema, cardiomegaly (heart weight = 558 grams) with concentrically symmetrical left ventricular hypertrophy, chronic nephrolithiasis, and moderate hepatic steatosis. Chemistry tests were positive for alprazolam (benzodiazepine), citalopram, and bupropion, all of which are anti-depressive but also may be used for other indications. The medical examiner ruled that the cause of death was drowning, but the disabling condition may be an acute cardiac event. The reported shortness of breath may have been due to pulmonary edema or cardiac dysrhythmia, which has been associated with cardiomegaly, LVH, and polypharmacy.
This 63-year-old, obese (BMI = 34.5 kg/m2) male, dived to 27 msw (90 fsw) with two buddies on a team. At depth, he signaled that he was having difficulties, aborted the dive, and made an emergency ascent before the two buddies could get to him. Upon reaching the surface, he appeared to be in distress and panicked. He was assisted to the boat, where he collapsed upon exiting the water. The boat crew started CPR and took him to the nearest ER, where he was declared dead.
He had a history of hypertension and diabetes. His autopsy revealed an enlarged heart with LVH, conspicuous pulmonary edema, serum positive for B-blocker, and significant coronary artery disease. Gas bubbles were present in the left heart but not in the right heart.
The likely disabling condition, in this case, is dysrhythmia, which led to cardiac arrest and death. Pulmonary edema did not appear significant, and clinical correlates for immersion pulmonary edema (IPE), cough, frothy, blood-tinged sputum, were not reported.
A 59-year-old obese (BMI = 33.1 kg/m2) male who was a smoker lost consciousness while diving at 24 msw (80 fsw) and drowned. He had trouble maintaining his buoyancy in an earlier dive and needed a guide’s assistance. He was seen struggling against the current and even trying to hold on to coral, but he did not appear to be in distress. He was found unconscious at the bottom with the regulator out of his mouth. Other divers in the area brought him to the surface and aboard where the crew began CPR. He was transported ashore and later declared dead. An autopsy revealed significant coronary artery disease, dilated heart, evidence of pulmonary barotrauma (bilateral pneumothorax, subcutaneous emphysema). His dive computer recorded a heart rate of 210 when he went into distress.
The probable disabling condition, in this case, was an acute coronary syndrome with arrhythmia. Contributing factors may have been exertion, stress, and the possible onset of pulmonary edema. The pulmonary barotrauma occurred on the ascent while the victim was already unconscious. This diver was probably not exercising regularly nor received formal exercise stress testing. Otherwise, he would have been aware of his poor fitness, and he may not have elected to dive in a strong current that required significant sustained effort.
A 60-year-old scuba diver collapsed upon boarding the boat after a 29 msw (95 fsw) dive. He had a history of hypertension, smoking, and was treated for depression. His medications included beta-blockers metoprolol, and anti-depressants Lamotrigine and Sertraline. The autopsy revealed severe left ventricular hypertrophy, moderate cardiomegaly, moderate coronary artery disease, and pulmonary edema.
The cause of sudden cardiac death in this case with LVH and cardiomegaly could have been an arrhythmia with a contribution of immersion pulmonary edema.
A 65-year-old female, experienced scuba diver, with a history of persistent atrial fibrillation, went into distress while spearfishing and lobster harvesting at about 23-26 msw (75-85 fsw). The water temperature was comfortable and the sea was calm. While adequately hydrated, she was wearing a tight-fitting wetsuit and indicated that she felt poorly 40 minutes into a dive that she had planned to last for one hour. She returned to the surface alone. At the surface, she was extremely dyspneic and weak. An alert crew identified that she required assistance to get aboard the boat. Unable to catch her breath, uncontrollably coughing up blood-tinged sputum, she eventually lost consciousness and pulse. CPR was initiated without success, and she was later declared dead.
We couldn’t obtain the autopsy report for this case. The victim used Xarelto, Metoprolol, Xanax, Amiodarone, Digoxin for her condition. She was a smoker. Her symptoms indicate immersion pulmonary edema. Her medications indicate significant cardiac problems and certainly could have contributed to its development.
A 62-year-old male diver was hunting for lobsters with his son. This was their third dive of the day, and the maximum depth was 27 msw (90 fsw). At some point, after they had reached 12 msw (40 fsw), the father gave a sign that he is going to the surface. His son did not notice any sign of distress, and he did not find it unusual because his father often finishes his dives without a dive buddy. The son did not surface with his dive buddy and instead joined another group for more lobster hunting. The victim appeared on the surface in distress alone and was recovered by alert boat crew and CPR initiated. He was evacuated to a recompression chamber, did not regain consciousness, and later died from a cardiac event. He had a history of atrial fibrillation that he reportedly had under control with an ablation two months before the accident, and was on medications. Autopsy revealed moderate to mild coronary artery disease and pulmonary edema, and no signs of pulmonary over inflation.
A 48-year-old male who was diving at a depth of less than 9 msw (30 fsw) drowned under ideal diving conditions. He was an experienced diver and felt that forming a three-person buddy team was adequate. The shallow depth, ideal conditions, and over three dozen other divers in the water gave further confidence to the decision. The other two divers in his team may have determined his professed experience did not warrant the usual vigilance and lost track of his whereabouts as he explored the reef. When they surfaced, they couldn’t find him. The crew started lost diver procedures, but they could not find the diver. His body was discovered many hours later, at the bottom not far from the entry site. There were no witnesses of his last minutes and no one saw him surface at any time. His dive gear appeared functional. The autopsy had no significant findings.
Most likely, he lost consciousness suddenly and sunk. A recording from his computer could have helped to establish if he attempted an ascent at any time. In the absence of known health history and unremarkable autopsy findings, it is not possible to establish what was the disabling factor in this case. It is also not clear whether his buddies lost sight of him when he sunk unconscious to the bottom, or he intentionally separated before getting in trouble.
A 56-year-old, experienced female diver was found unconscious and entangled in a fishing net at 58 msw (190 fsw) by a small group of divers diving together (loosely serving as buddy team). They found her with the regulator out of her mouth, tangled in fishing net upside down. They untangled her and, in a rapid uncontrolled ascent, got her to the surface. She remained unconscious since her discovery on the bottom despite receiving CPR. She was evacuated and treated unsuccessfully in a recompression chamber and was later declared dead. She had additional tanks of 50% and 100% oxygen for decompression. Her primary was air. The autopsy revealed minimal coronary artery disease, tympanic membrane perforation, subcutaneous emphysema, and cortical and brainstem hemorrhagic microinfarcts.
The disabling agent in this accident is the entanglement, while the disabling injury may have been asphyxia or hyperoxic toxicity. The ensnarling net may have pulled her regulator away and she either could not get to her secondary regulator and drown or mistakenly used either of her hyperoxic deco mixes. In her struggle, she may have inflated her legs, flipping her and further adding to her confusion. At this depth, nitrogen narcosis impairs the ability to handle emergency procedures as well as the efficacy of the buddy system. Despite it, buddies probably found the victim quite soon after she disappeared while she still may have been alive. In an attempt to take her to the surface, buddies at first failed to realize that her regulator was still entangled by the net.
They added gas to her BC, but she was not ascending until they finally freed her regulator. Now, with excessive positive buoyancy, she went emergently to the surface, which resulted in the rupture of her eardrum. It is not clear if she had arrived at the hyperbaric chamber alive, but she was recompressed to 50 msw (165 fsw) in an attempt to treat possible AGE and DCS. Five days later, the autopsy found subcutaneous emphysema and signs of micro-bleeding in the brain.
Diving at 58 msw (190 fsw) breathing air is risky, and the divers’ ability to cope with problems is diminished. Buddy diving may not be sufficient to mitigate the risks faced at this depth.
A 57-year-old male diver was on his third dive when he switched to another dive buddy as the teams entered the water. Both were experienced divers and they decided that buddy checks were not needed. They arrived at 40 msw (130 fsw) when the buddy noticed that the victim was not moving and regulator was out of his mouth. The buddy replaced the regulator and purged it twice without success. He attempted to drop the victim’s weights and inflate his BC when he lost hold of the victim who sank. His body was found and recovered by a remotely operated vehicle (ROV) in 91 msw (300 fsw) about three days later.
There were no problems before this last dive. The diver was carrying 30% nitrox in his main tank and possibly 40% nitrox in his pony bottle (empty, unable to analyze). The electronic gauge later determined that he used his main tank only for adding gas to his drysuit while he inadvertently was breathing from the pony bottle. This exposed him to the partial pressure of oxygen greater than 20 psi (1.4 bars), which is generally considered a safe limit.
Autopsy revealed left ventricular hypertrophy and significant coronary artery disease. Possible disabling conditions, in this case, are sudden cardiac death, running out of gas and drowning, and oxygen toxicity. His buddy was in the vicinity, and the fact that he was not alerted may indicate that unconsciousness was sudden likely in SCD. On the other hand, the running out of gas may have evoked a stress response, which, coupled with his significant coronary artery disease, may have led to dysrhythmia and unconsciousness. Nitrogen narcosis may have contributed and impaired his response to the emergency.
A 72-year-old obese male drowned while diving. He made a dive to 13 msw (43 fsw), and after a long surface interval began a second dive when his dive buddy noticed a hole in his BC and developed a leak. The buddy inflated her BC and brought him to the surface. He subsequently appeared panicked and confused and swam frantically away from the boat before losing his mouthpiece. His buddy swam up and noticed he was not breathing or had a pulse. She was unable to bring him back to the boat and recover him. She waved down a passing boat. Resuscitation efforts were unsuccessful. A medical examiner found cardiomegaly, mild to moderate coronary artery disease, and pulmonary edema.
Difficulty with his buoyancy vest throughout the dive with eventual leak and an uncontrolled emergency ascent is possible triggers in this accident, which resulted in arrhythmia and cardiac arrest. The autopsy found evidence of lung barotrauma or cerebral arterial gas embolism.
A 63-year-old female scuba diver experienced difficulties shortly upon entering the water. Before entering the water, her new buddy warned her that her BC hose was not connected. She said she would connect it. She entered the water with two buddies. One of the staff noticed her at the surface, shortly after the beginning of dive, with the regulator and mask in place, raising a hand. He asked if she needed more weight, but she did not answer, and she soon slipped underwater. One diver said she saw her weight belt sinking past her. It is not clear when the weight belt was dropped and who did it. When she looked up, she saw the victim ascending, but soon the victim started descending headfirst until reaching the bottom and did not interact with anyone around her. At one point, her buddies noticed her 6 meters (20 feet) away flailing. One diver who tried to assist her saw that the victim’s BC was not connected, and one rescuer attempted to inflate it manually. Divers brought the victim to the surface and within a few minutes staff got her out of the water and initiated CPR. Later, she was taken to the ER, where she was declared dead.
Failure to connect BC hose and negative buoyancy probably led to the drowning of this diver. Her brief appearance at the surface was classic for a drowning victim, unresponsive, hyper-focused, minimal activity, and eventual sinking. Her struggle with the buoyancy may have caused other disabling conditions like arrhythmia or immersion pulmonary edema.
A 66-year-old male instructor teaching an open circuit trimix course dived to 70 msw (230 fsw) with two students. The last dive was planned for about 19 min and 40 minutes of planned decompression. However, after about 6-7 minutes at the bottom, the victim left his student at depth and ascended rapidly. The victim surfaced in a panicked and confused state, was able to board the boat, and requested oxygen. He was assisted out of his dive gear and was provided high flow oxygen via a face mask. There was a 5 minutes ride back to shore, and he started to struggle with or reject the oxygen mask. His respiratory pattern appeared shallow and rapid and repeatedly made “Ahh” sounds as if in severe pain. He was confused and unable to focus. During the 10 minute wait for an ambulance at the dock, his level of consciousness began to decrease, and the muscles in his hands and arms began to contract. He became unresponsive and was believed to be in respiratory arrest while being loaded into the ambulance. He was transferred to a local hospital.
His bottom mix was 17/57 and had a travel gas of 30/35 down to 30 msw (98 fsw). He also had 50% and 100% deco gases.
He was transferred to a hospital with hyperbaric treatment ability and was given 4-5 treatments but remained in a comatose state. The victim was flown back to his home country (U.S.) in a comatose but stable state. An MRI revealed extensive swelling of the cervical spinal cord with diffuse bihemispheric white matter lesions and areas of restricted perfusion. Twelve days after the initial incident, he died due to cardiac arrest.
It is not known what triggered the emergency ascent in this case, but the dominant symptoms upon exiting the water were of severe decompression illness, which occurs after a rapid ascent from great depth and omitted decompression. The MRI findings may support the diagnosis of DCI. Fortunately, his two students were reportedly able to decompress properly and made it aboard without a problem.
A 71-year-old male diver was on a wreck dive to 58 msw (190 fsw). He became entangled and then freed. He then lost contact with the ascent line. He floated to the surface and collapsed on the ladder of the boat and was brought on board. He was given CPR for 90 minutes to no avail. There is speculation that he died of a heart attack. However, this was a severe decompression accident, and severe decompression sickness was very likely, not excluding the possibility of arterial gas embolism or heart attack.
A 46-year-old male diver was pulled from the water unresponsive after a deep wreck dive to 55-76 msw (180 – 250 fsw). His buddy noticed that he was struggling underwater, but the two of them could not locate the ascent line, and the victim did a rapid ascent. CPR was performed for two hours while waiting for the USCG. The USCG did not evacuate via helicopter due to the length of CPR.
The cause of the victim’s struggle at the bottom is not known. He may have died while ascending, from the condition causing him distress at depth. However, this was a severe decompression accident, sufficient to be the primary cause of death.
A 62-year-old female, experienced diver, lost consciousness while trapped and inverted at 20 msw (65 fsw).
She and her buddy were both experienced divers with hundreds of dives, but this was their first dive trip after a ten year hiatus. They reported to the dive operator that they were probably more experienced than most instructors. However, on day one, she discovered her drysuit no longer fit. She had considerable trouble with inflation/buoyancy on her first dive, required maximum assistance of the crew, and was overwhelmed to the point that she opted not to dive the rest of that day.
Subsequent dives were plagued by the inability to control her drysuit. At one point, she overinflated her drysuit due to difficulty overcoming the current and trapped her inflation bottle in the rocks. After freeing her, her buddy signaled that he was out of the air and was forced to make an emergency ascent without her despite making his situation known. Not finding his buddy on the surface, the out of air buddy felt he had to descend only to find her on the bottom signaling to him. He recovered her from the bottom but ran out of the air and was going to rely on his pony bottle to ascend.
Unfortunately, the buddy had turned off his emergency pony bottle. He signaled to her his urgent need for air, but she again failed to recognize the emergency or assist, and he made an emergent ascent almost losing consciousness himself. She finally recognized his plight and aided him on the surface. The boat crew made an emergent rescue and brought him safely aboard. The buddy pair did no further dives that day.
After two days of near-miss underwater incidents, they planned their next dive and decided to add the additional task of photography. Shortly after reaching the bottom, she was found inverted when her drysuit legs overinflated but remained at depth due to her weighting. She was unresponsive and not breathing. She was brought rapidly to surface by her dive buddy, who inflated her BC, dropped her weights [about 9 kilograms (20 pounds)], and kept her regulator in her mouth. She was not breathing from the time she left the bottom and had no pulse when checked onboard with an estimated 10 minutes from depth to boat. No rescue breaths were administered in the water. Blood tinged sputum was seen coming from her mouth. A crew administered CPR and attempted defibrillation three times during the initial 20 minutes of resuscitation without success. She was hoisted aboard the rescue helicopter that happened to be training nearby where ACLS continued with persistent asystole by monitor. The hoist was estimated to be 2 minutes in duration. She was taken to a recompression chamber and recompressed to 50 msw (165 fsw) without change and later declared dead. The autopsy revealed extensive lung barotrauma, bleeding in the petrous bones of the ears, and bilateral parietal subarachnoid bleeding. There was an insignificant coronary artery disease.
It is important to recognize deficiencies in training, physical fitness, and equipment. Even experienced divers who take an extended period away from diving, benefit from refresher dives. Even if the gear is in good working order, consider a replacement if it no longer fits or works effectively for you. Opting out of diving is the right decision when issues such as health, equipment, environment, etc. is a concern.
Avoid task loading until comfortable in the water. The multiple red flags should prompt one to put the camera away during this dive trip and concentrate on the basic skills. Drysuit diving requires proper equipment and training to use safely.
Possible causes for the loss of consciousness underwater:
Clear indications of the pulmonary over-inflation syndrome were evident on autopsy and may have impacted resuscitation, but they were not the primary cause of this fatality.
A 65-year-old, obese (BMI = 39 kg/m2) female, experienced diver, entered the water and began to panic as she descended, and attempted to remove her face mask. A fellow diver assisted her to the surface and struggled to keep the woman’s regulator in place. CPR was unsuccessful, and she was later pronounced dead.
She had no history of cardiac disease, medications, or recreational drug use. The autopsy found no significant atherosclerosis. Lungs were moderately edematous, which is compatible with drowning. The equipment appeared to be in good condition. We do not know if her tank valve was open when she entered the water and began sinking. The cause of death ruled by the medical examiner was drowning. We do not know what triggered a panic when she entered the water. The attempt to take off the mask underwater may be that the regulator did not provide air (tank valve closed) or that she experienced shortness of breath due to other causes.
A 63-year-old female scuba diver joined two others on a dive where she lost consciousness at depth over 30 minutes into her dive. She was brought to the dive boat, and later received CPR. The victim had a significant history of hemorrhage and hypertension. An autopsy showed a significant GI ulcer with chronic inflammation that resulted in over one liter bleed into her stomach.
Dramatic acute medical conditions like stomach bleeding may not always be predictable. They may occur unrelated to diving, but if they occur underwater and in a remote location that hampers timely evacuation, they are more likely to be fatal.
A 64-year-old male, novice diver, panicked while underwater. Upon reaching the surface, he struggled with buoyancy and removed his regulator. Due to the sea state and difficulty staying afloat, he eventually aspirated seawater before retrieval by the boat. The crew provided first aid oxygen and he remained conscious without signs of focal neurologic deficit or evidence of pulmonary barotrauma. He later developed a cough while his oxygen saturations remained low despite supplemental oxygen. His respiratory status quickly degraded despite intense respiratory support in the ICU, including mechanical ventilation. He eventually died.
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