Survival skills
A human being can survive an average of three to five days without the intake of water. The issues presented by the need for water dictate that unnecessary water loss by perspiration be avoided in survival situations. The need for water increases with exercise.
Winter swimming
Hypothermia poses a smaller risk. According to Tucker and Dugas, it takes more than approximately 30 minutes even in 0 °C water until the body temperature drops low enough for hypothermia to occur. Many people would probably be able to survive for almost an hour. There is no consensus on these figures however; according to different estimates a person can survive for 45 minutes in 0.3 °C water, but exhaustion or unconsciousness is expected to occur within 15 minutes. Consuming alcohol before winter swimming should be avoided because it speeds the onset and progression of hypothermia.