Trench foot (immersion foot) is a cold injury that occurs gradually over several days of exposure to cold, but not freezing, temperatures. The name comes from World War I troops who developed symptoms after standing in cold, wet trenches.
Signs and symptoms of trench foot include:
First aid for trench foot includes rewarming the affected areas, relieving pain, and preventing problems such as infection or dead skin (gangrene).
WebMD Medical Reference from Healthwise