Just because the weather gets colder in the winter doesn't mean the diving fun must end! However, cold water poses unique hazards due to how the cold affects our bodies and dive equipment.

HYPOTHERMIA

One of the most immediate and significant concerns is hypothermia, a condition that occurs when the body loses heat faster than it can produce it, leading to a dangerously low body temperature. Even in water as warm as 70 degrees, prolonged exposure can result in hypothermia due to water’s increased heat-conducting properties.

Wearing proper thermal protection is crucial. Additionally, divers should avoid prolonged exposure and plan shorter dives with frequent warming breaks when diving in particularly cold conditions.

Divers must be vigilant in recognizing hypothermia symptoms both in themselves and their buddies. Mild symptoms of hypothermia include shivering, numbness and a loss of coordination. As hypothermia progresses, the diver may experience slurred speech, disorientation, slowed heart rate and breathing, and ultimately loss of consciousness.

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Passive rewarming measures are sufficient for mild hypothermia. These measures help the body warm itself up by providing plenty of insulation in a dry and warm environment. Active rewarming measures may be necessary in more serious cases and involve providing external heat.

Common methods include drinking warm liquids and gently heating the core via warmed blankets or heating pads. Be careful with active warming as hypothermic divers may have dulled sense of touch and can be easily burned. Active heating may precipitate DCS.

In addition, applying heat only to the extremities can lead to a sudden drop in blood pressure. To prevent these complications, heat should be gradually and gently applied to the core before the extremities.

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DECOMPRESSION SICKNESS

DCS is another concern for cold-water divers. Colder temperatures cause peripheral blood vessels to constrict, which reduces blood flow to the extremities. This can affect the elimination of inert gases, like nitrogen, from the body during ascent, increasing the risk of DCS. Some manufacturers have developed heating vests to provide external heat to the diver. Research suggests that excessive use of these heating sources at depth may increase on-gassing, while a failure of these heating sources during the ascent may cause the diver to cool down and decrease off-gassing. Combined, these two conditions may lead to increased DCS risk.

To account for this phenomenon, divers should follow conservative dive profiles, allowing for slower ascents and incorporating safety stops to reduce the risk of DCS. Staying hydrated and avoiding alcohol before diving can also help maintain optimal circulation. Plenty of passive insulation is enough for most divers. For divers who require active heating, careful consideration should be taken to balance hypothermia risk against DCS risk.

EQUIPMENT CONCERNS

With regards to thermal protection, divers who are new to diving in drysuits should seek out training to learn how to manage buoyancy, flooding and other emergency procedures. Thicker undergarments and gloves, while making the dive warmer, can reduce a diver’s range of motion and dexterity.

While battery-operated heating systems are relatively reliable, batteries worn within a drysuit have the potential to ignite and are not accessible during a dive. Chemical hand-warmer–style heaters can lead to severe burns and should never be used on a dive as the chemical reaction that generates heat is accelerated with the increasing partial pressure of oxygen.

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Cold water also poses a potential risk of regulator malfunction, even if the water temperature is as warm as 50 degrees, due to the additional cooling as pressurized gas is released. This may lead to a regulator freezing and free-flowing; divers should be prepared to handle this situation.

While diving in cold water poses its own set of unique challenges, it also offers us the opportunity to see common dive sites in a whole new environment. Now that my drysuit is back from the shop, I can’t wait to give it a spin!