The Science of Peeing in Your Wetsuit

Nursing Diagnosis: Excessive voiding RT scuba diving AEB a warmer dive but also you stink.

I came across this article from that explains quite neatly why divers (and other watersport enthusiasts) pee in their wetsuits.

I like coffee. Especially on dive days. I want ammunition once I’m trapped in neoprene underwater. I tend to be cold on a normal day, topside. I actually get very uncomfortable underwater without proper preparation. Even then, I sometimes call a dive early due to my losing feeling in my toes. I stopped helping my instructor with her Open Water courses because the checkout dives are done in a spring-fed river, which may as well be an ice bath. I don’t like being cold. But I like coffee. So if I’m diving in a wetsuit, which I am unless the water is above 85 degrees F, I’m drinking coffee. And I’m gonna pee.


The link to the article above explains in science words why we pee in our wetsuits. It’s not just because we’re gross. There’s more. There’s actually a reason, and you are not responsible for your actions. Hallelujah!

In short, the authors explain that while we are diving, we experience “water loss due to immersion”, or immersion diuresis. The lower temperature of the water plus the increased pressure just squeezes it out of you. Underwater, your blood vessels constrict, and blood moves away from your extremities and toward your core. (This is why your fingers and toes are usually quite cold on a dive).

The increase in blood volume creates a cascade effect leading your kidneys to believe there is too much fluid in the body. So you keep peeing while your body tries to rid itself of excess fluid. This is another reason hydration is important!

BONUS Thoughts:

We just went over vasoconstriction and vasodilation in class today, so I’m going to share some relevant thoughts on immersion here. Vasoconstriction is the narrowing of your blood vessels (vasodilation is the widening of blood vessels). Water tends to be cooler than the air, causing your blood vessels to constrict. Underwater, your body is also exposed to a pressure gradient. The blood in your limbs shifts to the thoracic cavity, increasing the volume of blood in your chest. The heart then takes in more blood, all four of its chambers enlarging. The increased pressure on the right atrium increases the total cardiac output, slightly increasing your blood pressure.

Your body’s baroreceptors, which monitors changes in blood pressure, react by decreasing sympathetic activity. This is your “fight or flight” mechanism. Your heart rate decreases and so do your levels of epinephrine. Then your kidneys excrete more sodium, which increases your urine production.

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