Go on a dive trip, especially in a warm area, and you’ll most likely hear the dive guide or tour operator urge you to drink a lot of water. Because even though divers spend plenty of time submerged in it, water intake is paramount to our safety (and enjoyment) when we dive.
We often hear people say that they are “really dehydrated,” when all they really mean is that they’re thirsty. Most people in the industrialized world, who eat regularly, are rarely in any danger of actual dehydration. Dehydration is medically defined as a loss of body fluids severe enough to disrupt the body’s ability to maintain its normal functions, and in its severe form, it requires medical attention.
So while most healthy individuals living in the industrialized world rarely suffer anything but the slightest dehydration, there are a few things that can cause more severe, though usually not dangerous, levels of dehydration. Excessive sweating through rigorous exercise is one of them; diving is another.
Diving and Water
The body mainly loses water when diving because the diver is breathing very dry air. Air’s naturally occurring moisture is deliberately removed when it is compressed and put into dive tanks, as moisture may corrode the inside of the tank. This makes the air very dry, and the body uses its water reserves to compensate. Divers often complete several dives a day on vacation, of up to an hour or more, which can cause noticeable water loss. Diving also usually takes place in warm climates, which can cause additional water loss through sweating.
Symptoms of Dehydration
The first symptom of mild to moderate dehydration is typically a headache, which can be quite strong, comparable to a solid hangover. Further dehydration may cause dizziness, strong feelings of thirst and a lack of energy. Severe dehydration causes rapid drops in blood pressure, increased heart rate, or even unconsciousness. In its severe form, dehydration is considered a medical emergency that requires treatment, but even a mild case can take the fun out of diving, and headaches and dizziness can cause bad judgment calls during a dive.
Dehydration and DCS
Dehydration also increases the risk of decompression illness, or DCS. Dehydration causes a slowing of the body’s metabolic functions, a key part of managing and dispelling excess nitrogen upon ascent. Blood volume also decreases, and as the blood plays a vital role in transporting nitrogen to the lungs, and thus out of the body, this also compromises the body’s ability to handle the extra nitrogen stored in its tissues. Mild dehydration may not cause any notable increase in risk, but moderate and severe cases do. So proper hydration is an important part of dive safety.
Prevention and Treatment
Prevention is your best bet. Drink plenty of fluids, preferably water, up to a dive, and avoid excess caffeine. If you’re doing repeat dives, perhaps over several days, make sure you stay hydrated. Eating foods that are rich in water is also a good way of hydrating. Watermelon, cucumber and mangos are among the fruits and vegetables that are good for hydration. If you’re doing several dives a day in a warm, tropical climate, aim for up to a gallon of water a day.
Should dehydration set in, suspend strenuous activity for the time being, find a cool, shady place, and drink plenty of fluids. It can be beneficial to consume something salty, as this helps the body to better absorb fluids. Sports drinks or mixes containing minerals can also be a good choice to combat dehydration. Most pharmacies also sell packets of minerals and salts to mix with water, often used to treat dehydration in patients with diarrhea. Keep consuming extra fluids for the rest of the day, even after the immediate symptoms subside, and be aware of your water consumption in the following days.