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We identified 60 snorkelling deaths in Australia during the study
period. The three major causes of death were:
- Drowning (27 deaths, determined mainly from autopsy
results, but supported by information from witnesses and
resuscitation data where available);
- Cardiac events (18 deaths, determined almost
entirely from the autopsy report and conclusion); and
- Hypoxia from breath-holding after
hyperventilation and/or during ascent producing unconsciousness
and then drowning (12 deaths, determined by the sequence of events
prior to the death and information acquired about the victim's diving
technique).
In three cases, the cause of death was either uncommon or unknown .
Age: The average age of the 60 snorkellers who died was
44.7 years (SD, 18.7 years). Those who died of cardiac events had a
significantly higher average age than the group as a whole (56.6
years; SD, 14.6 years). The group who died of hypoxia was younger (35.2
years; SD, 14.9 years).
Sex: Fifteen of the 60 snorkellers were female. All
the snorkellers who died of hypoxia were male, as were 15 of the 18 who
died of cardiac events.
Status: Of the 27 who drowned, almost half were
overseas tourists, at least 10 of whom were non-English-speaking.
Nine of the 18 cardiac-event deaths also involved overseas tourists,
mostly from the United States. By contrast, the 12 snorkellers who
died of hypoxia were all Australians.
Experience: Of the 27 who drowned, 11 had no
experience or were inexperienced, while eight were either
experienced or very experienced relative to the circumstances in
which they died. Nine of the 18 who died of cardiac events were very
inexperienced and another three were specifically noted as being
either very unfit or extremely weak swimmers -- thus, at least 12 of
this group would probably have had difficulty with propulsion. All 12
who died of hypoxia had a minimum of two years' diving experience; at
least five were also scuba divers and one was an instructor.
Equipment problems: Flippers are necessary for
propulsion in ocean currents, and weights are often worn to
compensate for wetsuit buoyancy. Flippers were not worn by 11 of the 27
snorkellers who drowned and 16 of the 18 who died of cardiac events. Two
drowning victims became entrapped in speargun lines and one was
wearing a weightbelt with no quick release mechanism, while one
snorkeller who died of a cardiac event was possibly overweighted.
Most of the snorkellers who drowned remained on the surface after
death and thus were not overweighted. Among the 12 who died of hypoxia,
10 were predictably well equipped, although eight were overweighted
(this is a common practice among spearfishermen as it allows them to
descend more easily), and nine sank after death.
Medical disorders: Of the drowning victims, three
had epilepsy, three had asthma, one had bronchitis and emphysema.
Five were also noted as being very unfit physically, usually because
of major operations or illnesses. At least eight snorkellers who died
of cardiac events had a history of cardiac disease, including
cardiomyopathy (2), valvular disease (2), previous myocardial
infarction (3) and a triple coronary artery bypass graft (1), and six
were taking medication for hypertension and/or arrhythmias.
Disorders affecting those who died of hypoxia included epilepsy (1),
asthma (2), illicit drug use (2) and hypertension (2).
Contributory findings: Two of the 27 drownings were
associated with vomiting, and in three there appeared to be some
degree of saltwater aspiration before and contributing to the death.
Saltwater aspiration and vomiting preceding death were also noted in
some cardiac event deaths.
Circumstances: All 60 snorkellers were
recreational divers; 35 were snorkelling from a commercial charter
boat operation, and 15 were spearfishing. Only four snorkellers had a
"buddy" diver accompanying them at the time of the incident: most were
either diving alone (24), or had separated from others prior to the
incident (28).
Eight snorkellers died in less than 1.5 metres of water, and 41 died in
water five metres deep or less.
Cardiac event deaths seemed mainly associated with surface
swimming; in at least 13 of the 18 deaths, the incident occurred on the
surface and only two snorkellers were known to have descended under
water prior to the incident, while two died in water in which they could
have easily stood up.
The more experienced divers who died of hypoxia died in depths varying
from 3-15 metres. Most of those who died of hypoxia did so either
underwater or during ascent.
In 15 of the 18 cardiac event deaths, other snorkellers in the vicinity
observed no evidence of difficulty, despite six snorkellers
entering the water with a "buddy", four being observed by a supervisor
at the time, and three being part of an organised group.
Environmental conditions: Adverse conditions were
reported in association with nine drownings and five cardiac event
deaths.
Rescue attempts: There were no attempts at rescue in
25 cases, and in 35 a rescue attempt was made, usually by a nearby
swimmer. Rescue was initiated within five minutes (when
resuscitation is feasible) in only 10 cases, and at between five and 15
minutes in 23 cases. Details of rescue attempts were unknown for the
remaining two cases.
Cardiopulmonary resuscitation was attempted in 17 of the 27 drowning
deaths (usually with oxygen and usually by paramedics or medical
practitioners) and in 13 of the 18 cardiac event deaths.
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