There have been 81 patients brought to Treliske Hospital, Truro, UK in the last 6 years, having been rescued from near-drowning. Only 5 have been declared dead on arrival and not treated. We consider that hypothermia is a major factor in patients who have apparently drowned, particularly when it has been known that they were strong swimmers. In 1980, 45% of all drownings had rectal temperatures less than 35°C. The sea temperature around our shores varies between 5°C in January and 15.5°C in September. Hypothermia causes little problem until a central temperature of 35°C or less is reached. Between 35°C and approximately 32°C there is disorientation and incoordination, which may make swimming difficult to maintain efficiently. Below 32°C there is loss of consciousness; when this occurs, the victim's head drops below the water level and drowning occurs just as quickly as in a victim who is unconscious on entering the water.