How Cold is Too Cold?

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Written by DAN Staff

Whether you use a dry suit, a thick wet suit and/or warm thoughts to stay warm in cool water, it’s important to know how cold is too cold. Diving on a blustery winter morning can be fun, but pushing your body and your exposure protection to their limits can lead to serious consequences. Help your new divers and customers avoid putting themselves in harm’s way with guidance about how to stay comfortable underwater.

Letting one’s core temperature drop too low, leading to hypothermia or a near-hypothermic state, can affect dexterity, decision-making and the body’s ability to offgas. Because one of the first symptoms of serious hypothermia is diminished awareness, many individuals fail to recognize the symptoms until another diver draws attention to them. Know what to look for in yourself and your students to reduce the risk of mild hypothermia escalating into a life-threatening issue.

What is Hypothermia?

Hypothermia is a drop in core body temperature. It can obviously occur in the arctic, but can also happen in warm tropical waters if divers have inadequate exposure protection and a long enough exposure. The condition is of particular concern for people lost at sea and those diving in extreme conditions.

A typical adult maintains a core body temperature of about 37°C/98.6°F. When this core temperature drops below 35°C/95°F, hypothermia begins to set in, and the body’s function begins to be impaired. To keep the vital organs warm, the body will shunt blood to the core. The initial symptoms of hypothermia include shivering, loss of coordination, dizziness, nausea and feelings of hunger. If the core temperature is allowed to continue dropping, at 30°C/86°F many people will stop shivering and their pupils will dilate. At 27.8°C/82°F, muscles become rigid and a serious risk of cardiac complications arises. These symptoms worsen as the core temperature drops, so it’s vital that people suffering from hypothermia are taken to qualified medical care as rapidly as possible.

Learn to Beat the Cold

Hypothermia can be serious, but it’s not something a well-prepared diver should have to contend with in all but the most extreme situations. Plan ahead with appropriate exposure protection, heat sources and a well thought-out emergency action plan if things get a little too chilly. Bring hot water to make a warm drink or warm water to pour into your wet suit between dives to make yourself more comfortable on a day that’s more winter wonderland than diver’s paradise outside. If you or a student begins shivering, terminate the dive in a safe manner and take time to warm up. Consider whether anyone who was shivering will be warm enough for another dive. If not, come back on a warmer day – there’s no sense in putting anyone at risk.

For more information on safe cold-water diving practices, visit DAN.org/Health.

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