Survival in Cold Water
In comparison to other types of cold exposure, immersion in cold water encompasses a special set of biological concerns because of the rapidity with which the human body cools in water. Water has a thermal conductivity 22 times that of air and a heat capacity 3550 times that of air. Compared to marine mammals, such as whales, seals, and walruses, and aquatic Arctic animals, such as the polar bear, the ability of the human body to tolerate immersion in cold water is negligible. This poor tolerance of cold water is directly related to lack of body insulation, such as blubber, with which to retain the metabolic heat of the body. The point is amply illustrated by the appalling history of loss of life in shipwrecks at sea in the northern and southern latitudes of the world.
On Sunday night, April 14, 1912, the British liner Titanic struck an iceberg in the North Atlantic and sank in two and a half hours. The seas were calm and the sky clear at latitude 41° 46' N that night, but the water temperature was less than 0°C. Of the approximately 2207 people on board, only 712 were able to enter lifeboats. Although some passengers and crew members went down with the ship, perhaps 1000 people entered the freezing water wearing regular clothing and life jackets.