4 Reasons Divers Die
By Eric Douglas
The bad news: DAN's annual report on dive accidents highlights four factors common to
fatal accidents. The good news: They're all preventable.
Pop quiz: An overweight diver in poor physical condition returns to diving after a hiatus of
several years. He pulls his old gear off a shelf in the garage, hops on a dive boat and
attempts to dive on a current-swept reef at 80 feet. Anxious and struggling for much of the
dive, he burns through his air supply at an alarming rate. Upon discovering his tank is
nearly empty, the startled diver makes a rapid, barely controlled ascent to the surface and
suffers a fatal air embolism. What caused this accident?
You get an A if you answered "all of the above."
As this scenario-a composite of the accidents
found in the latest annual report of accidents
and fatalities from the Divers Alert Network (
DAN)-illustrates, fatal dive accidents often
have multiple and complex root causes.
Dr. Petar Denoble, DAN's research director,
puts it this way: "While each accident may be
different and some of them occur in an instant,
most accidents can be represented as a chain
of multiple events that lead to deadly outcome.
Removing any link from that chain may change
the outcome."
Based on the data contained in the 2006 DAN report (see "The DAN Report"), there are four
general contributing factors that can lead to fatal dive accidents.
Poor Diver Health
Almost any pre-existing medical condition or health factor can affect a diver's safety.
Common examples include obesity, heart disease, high blood pressure, breathing
difficulties (temporary or chronic), a general lack of fitness, pre-existing injuries and
dehydration. The biggest contributing factor-cited in 74 percent of the fatal cases covered by
the study-involved divers with a body mass index in the overweight, obese or morbidly
obese categories. And approximately 15 percent of fatalities examined by the study involved
people who were known to have high blood pressure or heart disease.
Today, diving is open to people with a host of medical conditions that a few years ago
would have prohibited them from participating in the sport. However, if you have one of
these conditions, it is important that you have your health regularly monitored and that you
manage your medical situation properly. Treated and controlled high blood pressure, for
example, may not create nearly the risk factors as uncontrolled high blood pressure.
Temporary health conditions like colds and severe allergies can also be problematic.
Whether permanent or temporary, any health condition that impedes your ability to be alert,
to recognize and respond to environmental conditions, and otherwise safely plan and
complete a dive should contraindicate diving. Even after you recover from your illness or
your chronic condition is back in check, your body needs time to recover from the effects of
your medical complication. For example: Your cough may be gone, but it may take time for
your chest congestion to clear. Rushing into the water before you're physically able to
breathe deeply can leave you starved for air, which may lead to panic. In this situation, trying
to breathe deeply when the body just is not able to causes you to feel as though you cannot
get any air at all. This leads to stress, which can lead to poor decision-making or worse,
full-scale panic.
Procedural Errors
Procedural errors common to the accidents covered in the DAN report include buoyancy
control problems, rapid ascents, missed decompression stops, general skill limitations,
ear equalization problems, and, most critically, failing to properly monitor the air supply,
resulting in low-on-air or out-of-air situations. In some cases, the diver lacked the
appropriate training for specialized activities like diving in the overhead environment of
caves or wrecks or deep diving. In other cases, the diver stayed within the scope of his
training, but his emergency response skills simply weren't up to the challenge.
In 26 percent of all the fatalities in the report, an emergency ascent was the precipitating
factor leading to the actual cause of death, but there were often other procedural errors that
triggered the ascent. Insufficient gas supply was the triggering event in 14 percent of cases;
the inability to deal with rough seas and strong current ranked second at 10 percent;
followed by health problems at 9 percent; entrapment or entanglement at 9 percent; and
equipment problems at 8 percent.
"Three critical words will help any diver be better prepared for dealing with a demanding
diving situation: practice, practice, practice," says Dan Orr, president of DAN and co-author
of the book Scuba Diving Safety (see "By the Book," p. 68). "The lack of diving experience or
skills or equipment that is unfamiliar adds to the stress of a demanding diving situation
and can lead to a task-loading situation resulting in an inappropriate reaction to a situation."
Illustration by Thomas-Bradley, LTD.
Environmental Issues
Open-water environments can change rapidly, and divers who are unprepared, out of
practice or physically incapable of adapting to those changes can become victims.
Before you dive, evaluate the air and water temperatures, currents, wave action, depth and
visibility, etc. Not all diving is the same. For example, if you are a warm-water diver making
your first cold-water dive, the effects of the water temperature can be a shock to you on your
first entry. Shallow-water divers are often surprised by how rapidly they use their air supply
and by the impact of narcosis on their first dives in the 100-foot range. Fighting an
unexpected current while exploring a wreck is no fun, especially if you lack good buoyancy
control, the ability to swim in a streamlined and efficient manner or lack the physical
endurance to fight that current.
Equipment Problems
While equipment failures account for relatively few fatalities covered in the DAN study, they
are one of the most predictable-and easily preventable-causes of fatal dive accidents.
According to the study, BC issues were involved in 7.5 percent of the fatalities; regulator
issues in 6 percent; weight systems in 5 percent; and mask, fins, dry suit and computer
failures were involved in less than 3 percent each. It is important to note that this does not
mean that the equipment failure actually caused the fatality. Ultimately, the diver's reaction
to an equipment failure is more likely to impact the outcome of the incident than the actual
failure itself.
Equipment issues are often obvious before the dive and the observant diver can effectively
make a preemptive self-rescue before he ever enters the water. The best policy is to check
your equipment thoroughly before you board the dive boat, maintain your gear carefully and
follow all recommended service intervals.
The DAN Report
The DAN Annual Diving Report (formerly called the Annual Report on Decompression
Illness, Diving Fatalities, and Project Dive Exploration) is compiled and published annually
by the Divers Alert Network, and is available to the public at no cost as a downloadable
PDF. Visit www.diversalertnetwork.org for more details. Reports from previous years, dating
back to 2001, are also available on the site.
The 2006 report that is the basis for this article covers accidents that occurred in 2004, the
most recent full year for which data was available. The 2007 DAN Annual Diving Report
(based on accidents from 2005) is scheduled for release later this year.
By the Book
Scuba Diving Safety Few books cover the
topic as broadly as this 185-page paperback
from Dan Orr, president of the Divers Alert
Network, and Eric Douglas, DAN's training
director (and Scuba Diving training columnist).
In the spirit of preparation-equals-prevention,
it runs the gamut from safe dive site selection
to in-water resuscitation, search patterns and
the steps for loading an injured diver into a
helicopter's rescue basket. Published by:
Human Kinetics. ISBN: 0736052518. Price: $21.95. -Travis Marshall
Diver Down: Real-World Scuba Accidents and How to Avoid Them In his monthly "Lessons
for Life" column, Scuba Diving Training Editor Michael Ange tackles the hard issues of dive
safety by analyzing real-world dive accidents. In Diver Down, Ange follows a similar format
to describe and analyze 20 dive accidents in chilling detail, each with a summary of
strategies for survival. Published by: International Marine/McGraw Hill. ISBN: 0071445722.
Price: $15.95.
Don't Be a Statistic
Seven tips for avoiding accidents.
-Eric Douglas
By Eric Douglas
The bad news: DAN's annual report on dive accidents highlights four factors common to
fatal accidents. The good news: They're all preventable.
Pop quiz: An overweight diver in poor physical condition returns to diving after a hiatus of
several years. He pulls his old gear off a shelf in the garage, hops on a dive boat and
attempts to dive on a current-swept reef at 80 feet. Anxious and struggling for much of the
dive, he burns through his air supply at an alarming rate. Upon discovering his tank is
nearly empty, the startled diver makes a rapid, barely controlled ascent to the surface and
suffers a fatal air embolism. What caused this accident?
You get an A if you answered "all of the above."
As this scenario-a composite of the accidents
found in the latest annual report of accidents
and fatalities from the Divers Alert Network (
DAN)-illustrates, fatal dive accidents often
have multiple and complex root causes.
Dr. Petar Denoble, DAN's research director,
puts it this way: "While each accident may be
different and some of them occur in an instant,
most accidents can be represented as a chain
of multiple events that lead to deadly outcome.
Removing any link from that chain may change
the outcome."
Based on the data contained in the 2006 DAN report (see "The DAN Report"), there are four
general contributing factors that can lead to fatal dive accidents.
Poor Diver Health
Almost any pre-existing medical condition or health factor can affect a diver's safety.
Common examples include obesity, heart disease, high blood pressure, breathing
difficulties (temporary or chronic), a general lack of fitness, pre-existing injuries and
dehydration. The biggest contributing factor-cited in 74 percent of the fatal cases covered by
the study-involved divers with a body mass index in the overweight, obese or morbidly
obese categories. And approximately 15 percent of fatalities examined by the study involved
people who were known to have high blood pressure or heart disease.
Today, diving is open to people with a host of medical conditions that a few years ago
would have prohibited them from participating in the sport. However, if you have one of
these conditions, it is important that you have your health regularly monitored and that you
manage your medical situation properly. Treated and controlled high blood pressure, for
example, may not create nearly the risk factors as uncontrolled high blood pressure.
Temporary health conditions like colds and severe allergies can also be problematic.
Whether permanent or temporary, any health condition that impedes your ability to be alert,
to recognize and respond to environmental conditions, and otherwise safely plan and
complete a dive should contraindicate diving. Even after you recover from your illness or
your chronic condition is back in check, your body needs time to recover from the effects of
your medical complication. For example: Your cough may be gone, but it may take time for
your chest congestion to clear. Rushing into the water before you're physically able to
breathe deeply can leave you starved for air, which may lead to panic. In this situation, trying
to breathe deeply when the body just is not able to causes you to feel as though you cannot
get any air at all. This leads to stress, which can lead to poor decision-making or worse,
full-scale panic.
Procedural Errors
Procedural errors common to the accidents covered in the DAN report include buoyancy
control problems, rapid ascents, missed decompression stops, general skill limitations,
ear equalization problems, and, most critically, failing to properly monitor the air supply,
resulting in low-on-air or out-of-air situations. In some cases, the diver lacked the
appropriate training for specialized activities like diving in the overhead environment of
caves or wrecks or deep diving. In other cases, the diver stayed within the scope of his
training, but his emergency response skills simply weren't up to the challenge.
In 26 percent of all the fatalities in the report, an emergency ascent was the precipitating
factor leading to the actual cause of death, but there were often other procedural errors that
triggered the ascent. Insufficient gas supply was the triggering event in 14 percent of cases;
the inability to deal with rough seas and strong current ranked second at 10 percent;
followed by health problems at 9 percent; entrapment or entanglement at 9 percent; and
equipment problems at 8 percent.
"Three critical words will help any diver be better prepared for dealing with a demanding
diving situation: practice, practice, practice," says Dan Orr, president of DAN and co-author
of the book Scuba Diving Safety (see "By the Book," p. 68). "The lack of diving experience or
skills or equipment that is unfamiliar adds to the stress of a demanding diving situation
and can lead to a task-loading situation resulting in an inappropriate reaction to a situation."
Illustration by Thomas-Bradley, LTD.
Environmental Issues
Open-water environments can change rapidly, and divers who are unprepared, out of
practice or physically incapable of adapting to those changes can become victims.
Before you dive, evaluate the air and water temperatures, currents, wave action, depth and
visibility, etc. Not all diving is the same. For example, if you are a warm-water diver making
your first cold-water dive, the effects of the water temperature can be a shock to you on your
first entry. Shallow-water divers are often surprised by how rapidly they use their air supply
and by the impact of narcosis on their first dives in the 100-foot range. Fighting an
unexpected current while exploring a wreck is no fun, especially if you lack good buoyancy
control, the ability to swim in a streamlined and efficient manner or lack the physical
endurance to fight that current.
Equipment Problems
While equipment failures account for relatively few fatalities covered in the DAN study, they
are one of the most predictable-and easily preventable-causes of fatal dive accidents.
According to the study, BC issues were involved in 7.5 percent of the fatalities; regulator
issues in 6 percent; weight systems in 5 percent; and mask, fins, dry suit and computer
failures were involved in less than 3 percent each. It is important to note that this does not
mean that the equipment failure actually caused the fatality. Ultimately, the diver's reaction
to an equipment failure is more likely to impact the outcome of the incident than the actual
failure itself.
Equipment issues are often obvious before the dive and the observant diver can effectively
make a preemptive self-rescue before he ever enters the water. The best policy is to check
your equipment thoroughly before you board the dive boat, maintain your gear carefully and
follow all recommended service intervals.
The DAN Report
The DAN Annual Diving Report (formerly called the Annual Report on Decompression
Illness, Diving Fatalities, and Project Dive Exploration) is compiled and published annually
by the Divers Alert Network, and is available to the public at no cost as a downloadable
PDF. Visit www.diversalertnetwork.org for more details. Reports from previous years, dating
back to 2001, are also available on the site.
The 2006 report that is the basis for this article covers accidents that occurred in 2004, the
most recent full year for which data was available. The 2007 DAN Annual Diving Report
(based on accidents from 2005) is scheduled for release later this year.
By the Book
Scuba Diving Safety Few books cover the
topic as broadly as this 185-page paperback
from Dan Orr, president of the Divers Alert
Network, and Eric Douglas, DAN's training
director (and Scuba Diving training columnist).
In the spirit of preparation-equals-prevention,
it runs the gamut from safe dive site selection
to in-water resuscitation, search patterns and
the steps for loading an injured diver into a
helicopter's rescue basket. Published by:
Human Kinetics. ISBN: 0736052518. Price: $21.95. -Travis Marshall
Diver Down: Real-World Scuba Accidents and How to Avoid Them In his monthly "Lessons
for Life" column, Scuba Diving Training Editor Michael Ange tackles the hard issues of dive
safety by analyzing real-world dive accidents. In Diver Down, Ange follows a similar format
to describe and analyze 20 dive accidents in chilling detail, each with a summary of
strategies for survival. Published by: International Marine/McGraw Hill. ISBN: 0071445722.
Price: $15.95.
Don't Be a Statistic
Seven tips for avoiding accidents.
- Dive within the limits of your training. Every year, divers who have never taken a
wreck, cave or cavern class die inside cave systems. Nearly as often, divers without
proper training die inside the overhead environment of wrecks, too. Get proper
training before attempting any dive above your skill level.
- Get the right gear. Whether it's wearing the correct exposure protection for
conditions or making sure you have the specialized equipment for a cave
penetration, the right gear can make a world of difference. All life-support equipment
should be properly maintained, serviced regularly and inspected before every dive.
- Take a refresher course. Even when diving within the limits of your training, take a
refresher course to shake off the rust from a long lay-off. A little time spent in the
pool before you take that trip-of-a-lifetime vacation will pay big dividends. You'll dive
safer and you'll have more fun because you will be more confident.
- Get rescue certified. Every diver should know how to respond in an emergency, but
the primary benefit of this class is that it will teach you to be responsible for your
own safety.
- Practice safety skills. Practice critical dive skills, such as flooding and clearing your
mask, recovering your reg, sharing air, etc.
- Stay in shape for diving. See your doctor about any medical condition that may limit
your ability to dive safely. Maintain a level of general fitness so you're prepared to
respond to any conditions.
- Stay within your personal safety envelope. Don't make any dive you're not
comfortable with. There is nothing wrong with saying no, at least until you have the
chance to get the appropriate training.
-Eric Douglas
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