Cold Water
Cold water is very life threatening to humans in a short time exposure. The body will lose its heat and thus temperature. When a person's temperature drops to the mid 80s a person can become unconscious and if not for a flotation device could then drown. Prolonged exposure, reducing the body temperature below 80° will result in death.
Cold water may be commonly thought to be in only northern climates, however, many scientists and experts define cold water as being under 70°. Consult life saving techniques for helping a victim of cold water exposure.