Cited Passage
The decreased strength, power, local muscular, and
overall cardiovascular endurance caused by alcohol may
become life-threatening detriments in an emergency diving
situation. For a diver who drinks and dives, an unexpected
problem (i.e., having to swim a great distance on the sur-
face, struggling against a strong current, rescuing another
diver, etc.) may intensify into a diving accident or fatality.
Alcohol is considered a factor in many drownings
and diving accidents. In analysis of large numbers of
drownings in the U.S. and Australia, about 80 percent of
the adult victims had elevated blood alcohol levels
(BAL). According to DAN Accident Report data,
approximately one-third of the reported diving accident
victims had consumed alcohol within 12 hours before or
after diving. Tests have also shown that some individuals
still have a BAL above the legal limit for driving 24 hours
after their last drink (Plueckhahn 1984). There are some
divers, therefore, who ideally should refrain from drink-
ing alcohol 24 hours before and after a dive.
It’s important to drink a lot of fluids before and
after diving, but those fluids should be water and fruit
juices, not alcoholic beverages. Alcohol is a diuretic,
i.e., a substance that causes greater loss of fluids than it
contains. Not only fluid, but essential minerals and
electrolytes are lost through diuresis (urination). Alco-
hol inhibits the brain hormone ADH (Antidiuretic Hor-
mone), creating a vicious cycle whereby the more
alcohol a person drinks, the more he urinates, which
leads to further dehydration. When the brain becomes
dehydrated, the individual experiences dizziness,
headache, and a “hangover” feeling.
For divers, dehydration resulting from alcohol con-
sumption poses a number of problems. Dehydration cre-
ates hypovolemia (thicker blood volume), resulting in
slower off-gassing of nitrogen. This makes alcohol a
major risk factor in decompression sickness, particularly
bends with serious neurological deficits. According to
DAN, there appears to be a relationship between an
increased number of drinks and the severity of decom-
pression illness. In a study on alcohol and bends, it was
reported that alcohol can reduce the surface tension, a
force which limits bubble growth, and therefore may
encourage bubble formation (Edmonds, Lowry, and Pen-
nefather 1992). Additionally, the vasodilation of capillar-
ies caused by alcohol may allow nitrogen to escape too
rapidly, increasing chances of decompression sickness
(DCS) even more.
Alcohol also predisposes a diver to thermal stress. As
alcohol dilates the peripheral blood vessels, circulation is
diverted to the skin and heat escapes. In cold climates, this
impairment in thermoregulation may deteriorate into a
life-threatening state of hypothermia.
One of the first signs of hypothermia is shivering,
which concurrently promotes a faster rate of nitrogen elim-
ination. In hot environments, alcohol can increase sweat-
ing, which leads to further dehydration, and precipitates
hyperthermia, a state of elevated body core temperature,
which can progress to heat stroke.
3-36 NOAA Diving Manual