Andy Torbet sets aside his usual frivolity to answer one of the key questions asked by anyone who ever donned a wetsuit.

The great question. One asked of us all since the dawn of time. Asked of divers and snorkellers by other divers and non-divers alike – ‘Do you pee in your wetsuit’?

Torbet on the Tube: Should you pee in your wetsuit?

Have you ever noticed that you seem to urinate more when you’re snorkelling than you normally would? Now if you’re being good this may have something to do with the fact you have ensured you are properly hydrated before entering the water… but most of us aren’t as good at this as we should be. So, there must be some other physiological response to immersion in water. And there is. In fact, more than one thing.

The first is usually talked about in reference to being able to hold your breath longer, as opposed to bladder control – the Mammalian Dive Reflex. This occurs not only in diving mammals such as seals and cetaceans but in all mammals studied to date, even those not normally associated with going underwater. In fact, all vertebrates studied so far have shown signs of a Dive Reflex and the subject is nothing new.

In 1879 the scientist Paul Bert reported that it took the duck he was holding underwater, one imagines forcefully, over 20 minutes to die of asphyxiation. Horrible, eh? I suppose they had a less enlightened approach to scientific experimentation back then. If you’re in any doubt take a look at what Haldane, the father of hyperbaric physiology, did to himself and his son…and sailors…and some unfortunate goats.

You can’t breathe underwater, and your body knows this. In humans, the Dive Reflex causes a number of physiological responses designed to preserve life as long as possible. Your heartbeat decreases and more red blood cells are excreted by the spleen into your system. But, critically to the ‘why do I pee more?’ question, your body then seeks to pull blood from your limbs into critical areas such as your vital organs and brain to make best use of the oxygen left in your blood.

This causes the areas that monitor blood volume, all situated in your torso, to think you have too much fluid down there. So your organs think you are over-hydrated, and force you to get rid of excess fluid via the normal exit route. All it takes is a dunking in water, so even if you’re snorkelling on the surface, not holding your breath, it’ll still kick in.

Immersion in water and the horizontal position we adopt while snorkelling also creates greater blood pressure in your middle compared to standing up on dry land. This has the same effect as before – your body thinks you’ve too great a blood volume and tries to push some of the ‘excess’ fluid out via the bladder.

The condition is further compounded by cold water. When we get cold one of our biological responses is to, just like in the Dive Reflex, pull blood away from the peripheries and into our vital areas – away from arms and legs and into the torso and head. Which, once again, creates an illusion of increased blood volume and a requirement to reduce this through urination.

In reality, it’s even more complicated than this and involves receptors in your heart, kidneys, hormones and factors medical science aren’t sure about. The main thing to remember about all of this, especially if you feel embarrassed by peeing in your wetsuit or, worse, be tempted to get out of the water and cut a great dive short because of a need to empty your bladder, there are only two types of snorkellers in this world:

  1. Those that admit they pee in their wetsuit.
  2. Liars!

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Article by Andy Torbet for SCUBA magazine, issue 82 September 2018.

Images in this online version have been substituted from the original images in SCUBA magazine due to usage rights. Featured image by Margaret Baldwin.

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