Source: Divers Alert Network (DAN)
Simply put, alcohol and diving are not compatible. Alcohol causes depression of the central nervous system, which impairs judgment and reduces reaction time and coordination. Often the individual is not even aware of the degree of impairment.
A review of more than 15 studies on the effects of alcohol on performance found that alcohol was involved in roughly 50 percent of all accidents in people of drinking age. In Diving and Subaquatic Medicine (Edmonds C, et al., 2002), the authors report that alcohol is associated with up to 80 percent of all drownings in adult males.
It takes time for alcohol to be metabolized and its effects to wear off. M.W. Perrine and colleagues studied a group of experienced divers and the impact of alcohol consumption on their performance. Their investigation found that the ability to perform skills while scuba diving was significantly compromised at a blood alcohol concentration (BAC) of 0.04 percent, which can be reached by a 180-pound man who consumes two 12-ounce beers in one hour on an empty stomach. The study went on to state that even at a lower BAC, situational awareness and protective inhibitions may be reduced.
Recent alcohol intake (along with seasickness, traveler's diarrhea, excessive sweating, diuretic medications and air travel) is a potential cause of dehydration in divers. Dehydration, particularly when severe, is a potential risk factor for decompression sickness (DCS). Diving can also contribute to further fluid loss through breathing dry air and diuresis caused by both immersion and cold. Some symptoms of dehydration, such as fatigue or drowsiness, can even mimic DCS, leading to possible diagnostic confusion.
Alcohol ingestion may also enhance the effects of nitrogen narcosis. Elevated BAC, dehydration and nitrogen narcosis together may result in otherwise preventable accidents due to decreased problem-solving ability.
Many divers appreciate a cold beer, but drinking and diving can turn a safe activity into a nightmare for both the diver and all those impacted by a rescue or fatality. Think twice before combining alcohol and diving.