Sudden immersion into cold water places a severe strain on bodily systems that can lead to cardiac arrest. Survivors of cold-water accidents have reported their breath driven from them on contact with the water. Anyone falling into cold water should immediately cover the mouth and nose with the hands to prevent inhaling water. Total disorientation may occur. The shock to the system may not allow the person to think or act clearly.
Cold water can quickly numb the extremities.
Cold hands may be unable to fasten the straps of a life jacket, grasp a rescue line, or hold on to an overturned boat. Everyone should always wear a life jacket. This becomes especially critical when boating on cold water. Cold water causes the body's temperature to drop. Lowering of the body's core temperature is called hypothermia.