Immersion diuresis

Immersion diuresis or urination in freediving

Diving into the underwater world is a unique experience that can bring a lot of pleasure and new impressions. However, one delicate topic that often causes embarrassment among divers and freedivers is urinating in a wetsuit. In this article, we will examine the physiological mechanisms behind this phenomenon and provide practical recommendations for comfortable diving.

Diuresis during immersion and its causes

One of the key physiological reactions of the body to being submerged in water is immersion diuresis. This process is caused by several factors:
  • Peripheral vasoconstriction: in water, blood vessels on the periphery of the body constrict, leading to the redistribution of blood to central organs, such as the heart, lungs, and large internal blood vessels. This causes a significant increase in blood volume in the pulmonary circulation, which the body interprets as an excess of fluid.
  • Increased blood pressure: the constriction of blood vessels and redistribution of blood increase blood pressure. The body tries to compensate for this increase by stimulating the kidneys to produce urine. Thus, urination underwater is a natural reaction of the body to changes in blood pressure.
  • Water pressure: at great depths, water pressure increases, which can also stimulate the kidneys to produce urine. The increased pressure enhances fluid filtration by the kidneys, leading to increased urination.
  • Water temperature: cold water intensifies immersion diuresis, as the body tries to conserve heat by redistributing blood to the central organs. This makes the issue particularly relevant for open-water dives, although prolonged stays in a pool can also trigger the urge to urinate.

The importance of hydration

One of the main aspects to consider in freediving is the need to maintain hydration. Since immersion diuresis leads to fluid loss, it is important to drink plenty of water before, during, and after dives. Dehydration can increase the risk of decompression sickness in divers and reduce blood oxygen capacity in freedivers. You can read more about hydration in the article "Improving performance in freediving: the importance of hydration".

Practical tips for comfortable diving

Now that we understand the physiology of the process, let's look at some practical tips to make your freediving sessions more comfortable.
  • Maintain hydration: drink water before starting your freediving sessions and during breaks between dives. Bring a water bottle with you and take a few sips after each dive.
  • Don't hold back urges: holding back can lead to urinary tract or bladder infections, especially in women. This painful condition can ruin your trip.
  • Wash your wetsuit after use: urine won't damage your wetsuit, but it's important to rinse it after use to avoid skin irritation and unpleasant odors. Use special wetsuit cleaners or antiseptics.
  • Urinate early in the session: this will give more time for the urine to be washed out of the wetsuit before the session ends.
  • Avoid strong-scented foods: asparagus, Brussels sprouts, onions, garlic, salmon, and any fish can intensify the smell of urine.

Myths and realities

There are several myths associated with urinating in a wetsuit that are worth dispelling:
  • Myth about wetsuit damage: urine won't destroy your wetsuit, but regular rinsing is important to keep it in good condition.
  • Myth about warming up: urinating in a wetsuit may temporarily warm you up, but it will lead to additional heat and energy loss. The best way to stay warm is to use quality gear and maintain hydration.


Immersion diuresis is a natural process driven by the body's physiological responses to being submerged in water. Understanding this process and following simple recommendations will help you enjoy every moment underwater without unnecessary stress. The main things are to stay hydrated, not hold back natural urges, and take care of your gear.

Remember, even Olympic swimmers admit to urinating in the pool, so there's no need to be embarrassed about this natural process. Your comfort and health should come first. By following the given advice, you can minimize unpleasant sensations and focus on the main thing—enjoying the underwater world.

We recommend taking a freediving course with us and you will discover new opportunities for personal growth and improve your skills, making each single-breath dive rich and unforgettable. Enjoy freediving and stay healthy!

© 2023 Apnetica
Sharm el Sheikh
Working hours: 9:00-17:00