Cold water shock likely causes more deaths than hypothermia. Cold-water shock is the result of sudden unexpected immersion into water 15 C. or below. With sudden exposure to cold water you could experience muscle paralyses. For 3 – 5 minutes after sudden emersion you will gasp for breath. You could experience muscle spasms, a rise in heart rate and blood pressure, or a heart attack. A person experiencing cold-water shock while still in the water may choke on the water, which presents a significant drowning risk.
It is critical that everyone on the boat wear a lifejacket at all times, because the cold water may numb and/or paralyse muscles and extremities, making it nearly impossible to grasp a rescue device or put on a lifejacket while in the water. The lifejacket is critically important to keeping you afloat and breathing. The treatment for cold water shock is the same as for hypothermia.