Staying Warm Underwater

How to Stay Warm Underwater

Staying warm during your underwater dives not only increases your comfort level but also reduces the risks of developing a life-threatening state of hypothermia.

Hypothermia is a condition of dangerously low body core temperature below 35 °C.

Scuba divers wear neoprene wet suits to offset the effects of being submerged in cold water for long periods.

Nevertheless wearing insufficient thermal insulation, too much neoprene, or the inappropriate exposure suit thickness and size causes discomfort and is potentially ineffective at keeping you warm and snug underwater.

Avoid the dangers of cold body temperature by following our five essential tips to help you stay warm underwater.

Signs of Premature Hypothermia

Assuming that your diving wet suit is not torn and in good condition, the most likely cause of shivering and feeling cold under water is a lack of insulation. Diving while you are cold is not fun and wrecks the enjoyment of scuba activities.

Heat energy is quickly lost and you risk exhaustion during the onset of hypothermia. Moving through the water becomes more difficult and you begin to feel numbness in your extremities.

When you feel like your fingers and toes are freezing it is almost impossible to perform the simple skills that keep you safe in the water. Operating your inflator button and kicking your fins is a major task.

If coldness deteriorates you increase the likelihood of making an error or suffering decompression sickness (DCS).

It's good if you recognize the early warning signs of deteriorating hypothermia. You are likely to act against the problem worsening and hopefully you will end the dive and seek warmth.

Your next dive is probably going to be different. You will wear better insulation with more body coverage. Wearing additional neoprene items is going to help you hold on to your normal body heat and the following five essential tips is our best advice to and stay warm and enjoy your future dives.

Five Essentials for Staying Warm Underwater


Few scuba divers enjoy wearing a hood to cover their head. Neoprene hoods usually feel restrictive and sometimes claustrophobic. Nonetheless would you go mountain skiing without a woolly hat?

If you are diving in cold water your head should be the first essential body part to protect from heat loss. Divers lose 30% of heat energy from their crown.

Even though your head is a relatively small surface area compared to the body, warmth is lost at a rapid rate because of the large blood supply to the brain. The blood flows close under the scalp and the cold ocean draws heat from your head via a process called convection.

If you get cold your body naturally constricts large vessels that carry blood to your arms and legs. The blood vessels that supply the brain do not get constricted and hence heat is dumped into the water at full capacity.

Your head is the most important part of your body to protect from contact with cold water. If you find wearing a neoprene hood uncomfortable try using a dry suit yoke-less style of hood or a beanie.

Beanies are head wear shaped like small bathing caps often with a chin strap. These two options increase thermal insulation without restricting mobility.

Wearing a shorty wet suit is really comfortable in most warm water environments but it can be dangerous in cold water dives. Your legs and arms and torso form large exposed surface areas that lose heat while diving.

Covering your upper body chest area with neoprene and leaving your arms and legs exposed to low temperature water is inefficient and somewhat dangerous.

It is better to cover your entire body skin surface with thin a neoprene full wet suit that covering your torso with a thick shorty and no protection for your bare limbs.


Scuba wet suits work by trapping a thin layer of insulated water between your skin and the cooler ocean. A leaking wet suit allows too much cold water inside the neoprene protection which results in rapid heat loss.

There are a number of reasons for a poor fitting leaky wet suit but the most common reason is wearing the wrong body size. The collar area needs to be a non-restrictive water-resistant seal against your neck.

The wet suit openings at your arms, wrists, legs, and ankles need to seal against your skin without limiting your movement.

If you want the wet suit to keep you warm you must keep the water out. Too much cold water entering the openings makes it worthless. Also pay attention to the collar seal, zippers and seams.

Broken or torn wet suits do not function as they are supposed to. The water channels should seal snugly without causing over tightness.

Wet suits wear out over time. The nitrogen bubbles inside the neoprene eventually break down losing their thermal qualities. Throughout regular deep diving the bubbles flatten which also reduces their protection.

During storage the neoprene is often attacked and weakened by chemicals in the air and from poor storage or maintenance. The point we are making is that wet suits should be replaced any time their quality is compromised.

You should expect to purchase a new wet suit every few years depending on its quality and usage.

The ultimate snug fitting wet suit rarely exists off-the-rack in the dive shop. If you're looking for near perfect fit and comfort consider having a custom made wet suit.

Custom suits mold to your body contours and you can add accessories like pockets, a spine pad or your favourite logo name.

Wet Suit Water Temperature vs. Thickness Guide

The wet suit thickness guide cannot calculate your age, weight, the quality of your wet suit or the depth you dive but it indicates the general thickness to keep you warm underwater.


A hot drink is always advisable before and after the dives. This helps to raise your body core temperature. We suggest a non-diuretic drink such as cocoa. Drinking alcohol and scuba diving do not mix well but it also causes you to lose more heat.

Try to retain your body heat before the dive by dressing in warm clothing. It is better to be a little too warm before the dive than starting too cold.

Heat loss is likely to accelerate the most during your surface interval. Your body is wet and you could also suffer wind chill. Remove your wet suit and try to towel yourself dry. Cover yourself with dry warm clothing such as a jacket, parka windbreaker or a raincoat to shield you from the sea breeze.


Diving in shallow depths of water has two distinct advantages. First as you dive deeper the increase in water pressure compresses the gas bubbles in the neoprene material of your wet suit.

This effectively makes the material thinner causing less insulation. Divers also chill faster when they breathe air under pressure so diving deeper relates to breathing higher pressure air which increases the chill factor.

In many diving spots deep water tends to have cold temperatures. The abrupt plunge in temperatures from only a few meters of extra depth can be alarmingly chilling. Sometimes divers are guilty of diving deep without a clear reason or objective.

Diving in shallow depths broadly provides more ambient light, coral formation and warmer water. It makes good sense and prudence to consider wearing a dry suit if the objective is to dive deep and the water is cold. Dry suit thermal qualities vastly improve underwater warmth for the diver.


Uncontrollable shivering is the danger sign which suggests the onset of hypothermia. If you begin to shiver underwater you should end the diving activities and surface as soon as possible. Early stages of hypothermia also increase your susceptibility to symptoms of decompression sickness (DCS).

Most dive tables and computer algorithms predict your blood flow rate to be constant throughout the total dive time. This is rarely an accurate prediction and in fact when a diver gets cold the flow rate is less stable and predictable.

Your body alters the blood flow through cold limbs which affects the elimination of nitrogen. Very often you 'off-gas' much slower when your body is cold which contradicts the dive plan of your table or computer.

Therefore, the risks of getting DCS increase because of the poor or slow removal of nitrogen gas that your body absorbed during the dive.

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