Scientists are aware you urinate in your wetsuit. While many people feel like this is weird, it’s completely natural. It’s the norm amongst surfers – even if they don’t all admit to it. As a waterman, you’re experiencing a unique underwater phenomenon called immersion diuresis. Don’t panic though. There is a totally legit scientific reason for this.

So, why do we pee in our wetsuits and what is actually happening inside your body?

Immersion diuresis, which literally means “water loss due to immersion,” is the culprit behind that urge to pee when you are in the water. Whether you are surfing, freediving, or just going for a swim, the lower temperature and increased pressure of the surrounding water makes you pee. It’s really as simple as that.

Immersion diuresis is a physiological response to being submerged in water and it’s actually part of the Mammalian Dive Reflex. When the body is immersed in water the colder temperatures and increased pressure from the surrounding environment causes a narrowing of the blood vessels (vasoconstriction) in your extremities. As a result of this vasoconstriction, your body moves blood volume away from your skin and extremities and redistributes it towards your core areas.


This increased blood volume, which is sent directly to your vital organs, triggers the inhibition of a vasopressin hormone that regulates the production of urine by the kidneys called anti-diuretic hormone (ADH). ADH essentially controls how much urine your kidneys produce and the increased blood volume being sent to your core areas tricks the body into thinking that there is a fluid overload (which kinda makes sense because you are surrounded by water). As a result, the body stops making ADH which triggers the kidneys to produce urine in an attempt to regain the fluid balance (ie. homeostasis) caused by that increased blood volume. So this is what really makes you pee in your wetsuit.

Now that you know this, peeing in your wetsuit is a totally legit thing to do – really it’s science. You have permission to no longer feel weird or ashamed. All the cool kids are doing it. Just make sure that you drink a lot of water before and after your session to avoid dehydration!

Note: This article was co-authored by Ian Towne