When a human is immersed in cold water, survival time is not measured in hours or even minutes, but often in seconds. It may sound counterintuitive, but very few people involved in cool- or cold-water emergencies actually die from hypothermia.

Hypothermia is a drop in the body core temperature, which is a function of temperature and time. Most drowning victims in cold water are dead long before hypothermia sets in. The reason for this is a phenomenon called cold shock.

Cold-Water Immersion

Falling into cold water causes instantaneous effects called cold water immersion. A significant percentage of people, even those with swimming skills and water experience, begin actively drowning from cold-water immersion in a matter of moments. The impairment of mental and physiological functions is so intense that it is critical to be prepared.

Cold-Water Gasp Reflex

The first and most critical stage of cold-water immersion is the cold-water gasp reflex. When thrust into cold water, a human will gasp uncontrollably in an involuntary physiological response. (Most of us have had this happen, such as when stepping into a cold shower or jumping into cold water.) This condition is extremely hazardous and is a major contributor of drownings in cooler water. A victim begins to hyperventilate, which increases panic and compounds their inability to breathe.

Mammalian Dive Reflex

Cold-water immersion’s second stage is the mammalian dive reflex, and it also has a rapid onset. When the body cools, capillaries constrict as blood is drawn from the extremities and shunted to the body’s core. This restricted blood flow rapidly affects fine dexterity. Simple tasks, such as pulling the toggle of a life vest or grasping a lifeline, become impossible.

Swimming Failure

The next stage of cold-water immersion is swimming failure, which can occur before or during clinical hypothermia. The restriction in the body’s blood flow from the dive reflex starves the larger muscle groups, weakening the victim. The inability to swim leads to drowning.

What You Can Do

Always wear a proper personal floatation device (PFD) and know how to use it. Try it on and read the manual. The opportunity to understand how your PFD works is when you are high and dry, not during an emergency.

To overcome the cold-water gasp reflex, hold your breath and try to keep from inhaling for as long an interval as you can. This is difficult to accomplish and can be managed only for a few seconds because the symptoms will continue to recur. However, if you maintain hold your breath for these short durations, the effects of the gasp reflex will slowly begin to ebb. Do not try and perform any other actions until your breathing is under control.

The HELP Position

There are a few simple techniques that can assist in lessening individual and group hypothermia. The technique that works best for individual hypothermia is the Heat Escape Lessening Posture/Position (HELP). Mastering the HELP position may be the single most important skill to survive a water emergency.

The technique is characterized by adopting the fetal position to lessen heat loss. Grab the front or back of your knees and keep your arms wrapped around them. (This cannot be accomplished effectively without a life vest or flotation aid.) Don’t squeeze too strongly. A moderate grip is sufficient, then simply lean your head back and float. The HELP position minimizes water flow across the body, lessening heat loss.

Enhancing this technique with a simple trash bag will extend survival time even longer. A 3-mil contractor-grade bag can be slipped on over your feet and works like a “poor man’s wetsuit”. Instead of heating the whole ocean, your body warms only the water in the bag. Trash bags take up little space and can be stowed easily in or on a life vest. Get entirely inside the bag, including arms and elbows, with just your head exposed. It is not a perfect solution, but this technique can keep body core temperatures elevated far longer than other techniques. You cannot effectively move in the HELP position, but saving energy is the point. Stay in this position inside the bag and just go with the water’s flow.

NOTE: Contractor’s bags are most often black, restricting visibility to rescuers, so consider investing in a large Halloween/pumpkin-style orange leaf bag. This one tip may be the most important and easiest survival advice for boaters and anglers. Bring 1-2 with you on any trip – land or water.

The Carpet Formation

If you are immersed with multiple survivors, the recommended group hypothermia mitigation technique is the Carpet Formation. This tactic allows the body’s core to float at the surface where the water is warmer. Survivors link arms with those on either side and interlock their legs with those across from them to share as much body heat as possible. (Give a right leg, take a right leg.) Grab the feet from the person in front of you and put their feet on your chest. Don’t let feet/legs dangle.

There are several benefits to this formation. It is comfortable, energy is saved, and survivors can last far longer. Because there are so many points of contact, it keeps the group together, which raises morale. In fact, multiple members of the group can fall asleep or become unconscious, and the formation will stay together. It also creates a platform for an injured survivor or someone without a life vest to rest on. This formation also makes a larger target for rescuers to find, and allows for 360-degree skyward visibility, which means survivors can keep watch for rescue vessels or aircraft.

Ben Rayner is executive director of Water Emergency Training, Inc. (wateremergencytraining.org), a nonprofit organization dedicated to saving lives through drowning-prevention education and training.

This article was originally published online in February 2018.