We think of running, cycling and triathlons as physical activities where hydration is absolutely critical. But scuba diving does not seem to have that same critical need, so hydration tends to be downplayed by scuba divers, reduced to just a “good practice” when going diving. Think again! In this article we will explore why proper hydration is so vital to healthy scuba diving. We will explore the many ways divers lose water during scuba diving activities, how dehydration can negatively affect diver performance, and how to recognize dehydration. Finally, we learn several tips for effectively keeping properly hydrated for your dives.
THE GENERAL NEED FOR WATER
It’s no secret that our bodies depend on water for survival. In fact, water makes up over half of our body weight. Every cell, tissue and organ in your body depends on water for proper functioning. Water is essential for joint lubrication, cardio-vascular efficiency, regulating temperature, and removing bodily waste.
You may have heard a common rule-of-thumb for water consumption to be “8 x 8” or eight 8-ounce glasses of water daily. However, more clinical recommendations advise between 3 and 4 liters of water per day for men, and between 2 and 3 liters of water per day for women. But there are many factors that may demand significantly more daily water intake including age, body mass, medications, alcohol or caffeine consumption, hot/dry climates, and physical activity.
HOW DO WE LOOSE WATER SCUBA DIVING?
Let’s take a look at some of the well-known and not-so-known factors that reduce hydration levels when engaging in scuba diving activities:
Sweating (climate) – Diving often takes us to tropical locations with the greatest abundance of coral reefs, as they are near the equator with good sun coverage and warm waters. With the lower latitudes comes warm, humid, tropical climates that increase sweating. But even in our northern latitudes, divers may sweat just carrying gear bags and tanks, and suiting up for their dive. Sometimes northerners come to the tropics for their once-a-year dive vacation and they are not at all accustomed to the oppressive humidity and do not do such a good job staying hydrated.
Sweating (exposure suit) – Also, no matter the latitude, divers wearing wetsuits will sweat under every square inch of that neoprene. So when we see a diver wearing a wetsuit or drysuit and he has a few lines of sweat running down his face, don’t be fooled. Underneath that exposure suit he is sweating more than the exposed skin where air is evaporating sweat and cooling the skin. A steady increase of body temperature takes place the longer the exposure suit is worn out of the water. Sweating underneath the exposure suit can be profuse, but it is hidden, making it quite deceptive.
Respiration – Our bodies naturally loose water through exhalation. You can notice this just exhaling on glass and seeing your exhaled water vapor create a fog on that glass. But when scuba diving, water loss through respiration is increased significantly due to our breathing of highly filtered and very dry compressed air. This air, with virtually no humidity, draws even more water out of the body during respiration.
Sun – Our best dive locations have excellent sunlight. As we engage in this outdoor activity we are susceptible to large amounts of sun exposure. A mild to moderate sunburn leaves the skin red, hot, and painful. Just as with any other skin burn the body rushes fluid to the skin. Being outdoors air will evaporate the moisture on the skin, leading to further fluid loss.
Wind – Because scuba diving is an outdoor activity another natural factor contributing to dehydration is wind. Not only do the tropics have healthy breezes, but a swift boat ride to a dive site can remove surface moisture and sweat from exposed skin. The faster the wind, the higher the rate of evaporation.
Salt – The majority of scuba diving takes place in salt water. So divers have contact with salt directly on their skin before, during, and after their dives. When we dive we are immersed in salt water and when we return to the surface, unless we rinse off thoroughly with fresh water, there will be salt water on our skin which evaporates leaving small salt crystals on our skin and hair. Before or after the dive we may be blown with salty ocean breezes or even salt spray when the boat hits waves. Since salt is hygroscopic it has the ability to attract and hold water molecules. When it sits on our skin it can pull water away from the skin tissue, where it quickly evaporates.
Immersion Diuresis – A technical term for “peeing in our wetsuits”! As we dive, ambient water pressure and the cooler temperature of water may both have a role in shunting blood from the extremities (arms and legs) into the thorax. When the body recognizes the increase of blood around core organs, and the subsequent increase in blood pressure, it attempts to flush fluids by increasing urine output. That is the reason for the frequent need to urinate during dives.
Vomiting – If you’ve spent time on a dive boat, you understand the plight of those who are plagued with sea sickness. Not only is it embarrassing and uncomfortable, but vomiting can leave the body in a severely dehydrated state along with a severe electrolyte imbalance. The more one vomits, the greater the chance of severe dehydration.
Alcohol – Dive trips are often fun, tropical vacations. It is important to recognize that drinking alcoholic beverages is quite common during dive vacations. Alcohol consumption actually counters water consumption since it is a diuretic. Alcohol diuresis is increased urine output resulting from the consumption of alcohol. The alcohol suppresses production of the body’s anti-diuretic hormone leaving the person with a frequent need to urinate, speeding up the loss of fluid from the body, and leading to dehydration.
HOW DO I KNOW IF I’M DEHYDRATED?
There are several symptoms of dehydration that you should be aware of:
- Little or no urine, or urine that is darker than usual
- Dry mouth
- Extreme thirst
- Sleepiness or fatigue
- Feeling dizzy or lightheaded
Do not wait until these symptoms appear before you take in water! Drink early and often. Also note that these symptoms may be hard to recognize when you are already dehydrated.
HOW DOES DEHYDRATION AFFECT DIVERS?
Picture an automotive television commercial for motor oil. They show the internal engine parts sluggishly moving with the thick, pitch-black oil junking it up. But then the new light-colored golden motor oil makes its way into the engine and now it moves faster, with greater efficiency. I use that visual to describe what your blood is doing with your organs when you are dehydrated. As the blood gets thicker due to reduced water, the circulatory system becomes compromised. Its ability to transport nutrients and blood gases such as oxygen, carbon dioxide and nitrogen diminish. This leads to muscle fatigue, cramping, high blood pressure, rapid heart beat, confusion, and increased breathing. And, as the circulatory system is vital to the off-gassing of nitrogen, nitrogen release may be compromised in a dehydrated diver. Mild to moderate dehydration in divers can lead to the following:
- Weakness and exhaustion
- Poor air consumption
- Reduced awareness
- Increased risk of decompression sickness
BUT WHAT TO DRINK?
Water is best. If you don’t like plain water, you can add small amounts of fruit juice for flavoring such as squeezing a lemon wedge or an orange slice. Sports drinks like Gatorade® or Powerade® are also good for hydration when engaging in long-duration physical activity, and so they have a high sugar content. That high sugar content prevents them from being your daily water intake. But they do contain sodium and other electrolytes, which are good if you’re sweating heavily, slightly dehydrated, cramping, or after vomiting. And finally, energy drinks like Red Bull® and Monster® – just stay away from them. There is no need to take in stimulating beverages prior to scuba diving.
TIPS FOR PROPER HYDRATION
Here are some tips on staying properly hydrated when scuba diving, plus links to items I actually use:
- Hydrate early, at regular intervals, hours before your dive.
- Carry a re-usable, clear, BPA-free water bottle with measurement markings. This helps you gauge your consumption. My favorite is the CamelBak BPA-Free Chute Bottle.
- Hydrate during surface interval times (SIT).
- Remember, fruit contains water, fructose and vitamins and is great both pre-dive and post-dive.
- Utilize shade as much as possible, especially for equipment set-up.
- Remain out of exposure suits until absolutely ready to get in the water.
- Apply sunscreen liberally and every one hour of sun exposure. Waterproof sunscreen is not waterproof. Being underwater, rinsing off, and sweating gradually removes sunscreen. Use SPF 30 or higher (I recommend higher).
- Cover up. Utilize wide-brimmed hats like the Columbia Bora Bora Sun Hat. Light-weight long-sleeve shirts or wind breakers are good for windy conditions, my favorite is the ExOfficio Reef Runner Lite Long Sleeve Shirt.
- Rinse the salt off your skin soon after diving.
- Do your best preventing sea sickness. Look into medication or using your sea legs. (See How to Get Your Sea Legs article)
- If vomiting occurs remember to replace fluids and electrolytes soon thereafter.
- Avoid diuretics, especially alcohol.
- Plain water and sport drinks: GOOD Energy drinks: BAD
As you can see hydration is really important in scuba diving. Keep up with your water intake and your body will keep up with you.