Hydration and Scuba Diving

It seems strange that a sport carried out in water can leave you dehydrated, but there are many ways divers lose water whilst diving. Dehydration can negatively affect diver performance and increase the risk of decompression sickness, so you need to know how to recognise dehydration. 

Why do we need water?

Water makes up over half of our body weight so our bodies depend on water for survival. 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.

Everyone has heard the advice, "Drink eight 8-ounce glasses of water a day." That's about 1.9 litres. However, the Institute of Medicine advises 3 litres of water per day for men, and  2.2 litres of water per day for women.  But you may need to vary that amount depending on your environment eg warm climates, your age, the amount of exercise you do and your general health and fitness.

Why do you become dehydrated when scuba diving?

All the following factors reduce the amount of water in your body:-

Sweating (climate) – Diving often takes us to warm locations with the greatest abundance of coral reefs, as they are near the equator with good sun coverage and warm waters. Divers come to the Cyprus for their once-a-year dive vacation and they are not used to the heat or the need to keep hydrated. But even in cooler countries, divers may sweat just carrying gear bags and tanks and from kitting up for their dive.

Sweating (exposure suit) – Divers all over the world sweat in their suits – wetsuits or drysuits! Sweating underneath the exposure suit can be profuse, but it is hidden, making it quite deceptive.

Respiration – Our bodies naturally loose water as you breathe out. We breathe dry compressed air when diving so the water lost through respiration is even greater.

Sun – Our best dive locations have excellent sunlight.  Whilst diving we are often outside in the sun for prolonged periods. Even mild sunburn causes the body to send water to the skin which then evaporates leading to further fluid loss.

Wind – Not only is it windy in the afternoon in Cyprus but a quick boat ride to and from a dive site can remove further moisture from the exposed skin.

Salt – Our diving in Cyprus takes place in salt water.  So divers have contact with salt directly on their skin before, during, and after their dives.  Unless you rinse it off, the salt crystals will sit on your skin and absorb water from your skin.

Immersion Diuresis – As we dive, ambient water pressure and the cooler temperature of water may both have a role in shunting blood from your arms and legs into your main body.  When the body recognises 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 – vomiting can leave the body in a severely dehydrated state along with a severe electrolyte imbalance.  The more you vomit, the greater the chance of severe dehydration.

Alcohol – Dive trips are often fun vacations.  It is important to recognise that drinking alcohol is quite common during dive vacations.  Alcohol is a diuretic, it makes you urinate more and so speeds up the loss of fluid from the body leading to dehydration.

Am I dehydrated?

There are several symptoms of dehydration that you should be aware of:

·        Little or no urine, or urine that is darker than usual – have a look at chart in our Wetstore toilet

·        Dry mouth

·        Headache

·        Extreme thirst

·        Sleepiness or fatigue

·        Confusion

·        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.

Why should divers be concerned about dehydration?

As the amount of water in your body decreases your blood gets thicker and so its ability to move gases around the body reduces. This can lead to muscle fatigue, cramping, high blood pressure, rapid heartbeat, confusion, and increased breathing.  The circulatory system is vital to the off-gassing of nitrogen, so 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

·       Cramping

·       Reduced awareness

·       Increased risk of decompression sickness

What can you drink?

Water is best.  If you don’t like plain water, add small amounts of fruit juice for flavouring.  Sports drinks like Lucozade® are also good for hydration when engaging in long-duration physical activity although they have a high sugar content, but they do contain sodium and other electrolytes. Energy drinks like Red Bull®, Shark® and Monster® contain high amounts of caffeine – a diuretic and so are best avoided before diving. 

How to stay hydrated

Here are some tips on staying properly hydrated when scuba diving:

1. Start drinking water hours before you go diving. DAN Europe also recommend drinking 200ml of water every 20 minutes after diving to ensure you stay hydrated.
2. Carry a re-usable, clear, water bottle so you can measure how much you are drinking and so avoid plastic rubbish.
3.  Hydrate during surface interval – use the water machine in the shop – if it is empty ask a member of staff to refill it.
4.  Fruit contains water, fructose and vitamins and is great both pre-dive and post-dive.
5. Stay in the shade as much as possible, especially when building your kit.
6. Don’t put your exposure suit on until the last minute, take your lead from our instructors.
7. Use sun cream to help prevent burning, wear a hat on the boat.
8. Cover up, wear a thin long sleeved shirt and trousers.
9. Rinse the salt off your skin as soon as you can after diving.
10.  Do your best preventing sea sickness.
11.  If vomiting occurs remember to replace fluids and electrolytes soon thereafter.
12. Avoid diuretics, especially alcohol. If you need to drink before diving we recommend no more than 2 cans of beer or equivalent the night before a dive. 
13. Plain water and sport drinks are good for hydration, energy drinks are not.

As you can see hydration is really important in scuba diving.