The air temp is 90° and the water a balmy 80° – so you forgo your wetsuit or just wear a lightweight skin. After all, it’s hot in the tropics and you can’t wait to cool off underwater.
Ahhhh….it feels so good to descend away from the scorching sun and hot, humid air into the cool, tropical sea. You’re cruising around, exploring the reef. It’s a fairly shallow drift dive, so you barely have to exert any energy swimming and know you’ll get to stay under for quite a while.
Then you start to feel a little chilly, no biggie, right? You still have at least 25 minutes of air, so you shrug it off.
A few moments later, your body starts shivering and you’re suddenly feeling kind of tired, and your arms and legs are having trouble navigating through the water. By the time you reach the surface, you’re freezing, disoriented, and your body is seemingly out of your control.
It seems absurd on the surface, doesn’t it? Diving destinations are, for the most part, exceptionally warm with blaring sunshine and a tropical climate, so how can hypothermia even be possible in these beach vacation conditions?
It all relates to your core body temperature.
Hypothermia can occur when your core body temperature drops below normal, which is 98.6 degrees, and your body’s internal heating mechanisms can’t compensate for the heat loss. Making up for this loss is an easy feat for all humans on land, but water draws away heat from a body roughly 25 times faster than air, so once submerged on a long dive, your body is losing heat much faster than it can be produced. The end result is mild hypothermia, and it’s been reported in waters as warm as 90 degrees.
It’s surprisingly common, and often overlooked as other concerns, (like decompression sickness), tend to garner more attention. But most problematic is that is can be difficult to identify.
Unlike traditional hypothermia, which has a fairly obvious onset, warm water hypothermia is often referred to as the “silent hypothermia” because it can be tricky to pinpoint as it occurs. The core temperature drops so slowly in these conditions that a diver might still feel perfectly warm while the body’s heating mechanisms are struggling to keep up. Even shivering – an internal thermo-regulator system – might not be present until hypothermia has set in, and an onslaught of symptoms suddenly arise.
Through a combination of prevention and awareness. Just being aware that it can occur, and knowing what symptoms to look for, is a giant first step to stopping hypothermia before it sets in.
These symptoms are general, but noticeable with a little vigilance, and can include:
When this occurs, go to the surface immediately, dry off, and spend more time on the boat that you normally would just warming up. (Even if it means missing a secondary dive that’s scheduled soon after your last one.)
With warm weather hypothermia, just being aware that it can happen in tropical climates is a good start to avoiding it. Have an arsenal of protective gear, give your body opportunities to warm up after a dive, and stay attuned to the signs your body is telling you. With a little common sense, it’s easy to avoid this surprising, but very real, risk.
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Have you ever experienced hypothermia while diving? Let us know in the comments section below!