Staying hydrated is important to the proper function of every cell, tissue and organ in a person’s body. Most of us have heard the 8×8 rule, the basic guideline of consuming eight 8oz-glasses of water per day. But life is busy, and hours can easily slip by between sips of water. In most cases, the resulting mild case of dehydration is rectified after a glass or two of water, with no serious consequences. But for a scuba diver, even mild dehydration can become dangerous.
How does dehydration effect scuba divers?
Dehydration predisposes a diver to decompression sickness (DCS). To understand why this is true, it’s important to first know the basic effects of dehydration on the body: A lack of water in the body thickens the blood, compromising the circulatory system by diminishing its ability to transport nutrients. As the exchange of gasses like oxygen, carbon dioxide and nitrogen diminishes, so does the body’s ability to off-gas nitrogen. So when a dehydrated person goes on a dive, his body is not efficiently ridding excess nitrogen accumulated at depth. Even if he dives within his computer limits and even if he ascends slowly at the end of the dive, he could have more residual nitrogen in his blood and tissues than normal. And if he reaches the surface safely, the increased excess nitrogen could trigger DCS on repetitive dives later that day.
In addition, dehydration can induce muscle fatigue and cramping, high blood pressure, confusion, accelerated heart rate, and rapid breathing. In a scuba diver, these symptoms lead to weakness and exhaustion, poor air consumption, reduced awareness, and the increased risk of decompression sickness.
Can scuba diving actually aggravate dehydration?
There are many factors in a diving day that compound dehydration. The intense sun and tropical air of popular dive destinations feel hot, especially for vacationers coming from cooler locations. Sweating is the body’s attempt to regulate its core temperature. And we sweat profusely stuffed in a wetsuit, preparing for a dive on the deck of a boat where there is little shade or trudging with heavy gear on our backs across hot sand for a beach entry dive.
Salt water effects a dehydrated diver. After being immersed in sea water, we’re covered with salt crystals whose hygroscopic properties draw moisture out through the skin. Even the sea spray that blows on us as the boat hits waves going to and from the dive site adds to our contact with salt water.
Everyone loses body moisture when they exhale, but the amount of moisture lost increases when a diver breathes compressed air. Most all moisture has been filtered out of the air when it traveled through the compression system and into the scuba tank. On a dive, this virtually humidity-free air draws moisture from a diver’s body during respiration.
Even a dehydrated diver feels the need to “go” during a dive, due to a phenomenon called Immersion Diuresis. Basically, water temperature and pressure during a dive cause the body to direct blood away from the arms and legs and toward the trunk, in an attempt to maintain core body temperature. This increase in blood levels around the major organs is detected by the kidneys and misinterpreted as excess fluid. Urine production increases in an attempt to flush the body of these excess fluids.
How to Stay Hydrated While Scuba Diving
- Drink ample amounts of water in the days leading up to the dive. Bring a water bottle with you to hydrate before and after the dive, and during surface intervals. You can also eat fruits during surface intervals to replace lost fluids.
- Avoid excessive amounts of alcohol and caffeinated beverages, as these diuretics flush water from the body.
- Rinse skin and hair with fresh water as soon as possible following a dive.
- Apply sunscreen after a dive and every two hours during sun exposure. (The body pulls moisture from other parts of the body to soothe sun-burned skin.)
- Stay in the shade, if possible.
- Put on your wetsuit at the last minute, when you’re ready to get into the water.
- Avoid seasickness if you’re susceptible by having medication on hand.
- Don’t dive hung-over.
Hydrating your body is always important. But a scuba diver must avoid dehydration because the risk of decompression sickness increases when the level of body moisture decreases.