A condition which develops following prolonged immersion of the feet in cold or cool water. It was commonly seen during the Second World War in shipwrecked sailors and airmen who had crashed into the sea, spending long periods there before being rescued. Such prolonged exposure results in VASOCONSTRICTION of the smaller arteries in the feet, leading to coldness and blueness and finally, in severe cases, to ulceration and GANGRENE. (See also TRENCH FOOT.)