A wise man once told me “there are two kinds of divers in this world: those who pee in their wetsuits, and those who lie about it…” but is this actually true? And if it isn’t, what are the moral consequences for those of us that do indulge in a little ”accidental leakage” from time to time?

For me personally, this is one of the key questions of the 21st century, and one that has bothered the minds of divers, spearfishers, open water swimmers and surfers alike ever since the invention of neoprene back in 1930. As usual, here at Freedive Earth, we’re not afraid to tackle the big questions, and we’ve broken the problem down into two parts. First up, it’s the (by now) world famous Dr Otter with the physiological perspective.

Intra-Wetsuit Urination, the Physiological Perspective

Hi there everyone, happy new year! And what better way to start things off than with our old favourite, the mammalian dive reflex?

As we’ve discussed before, the mammalian dive reflex is one of the key physiological adaptations that allows humans to reach truly amazing depths with comfort and safety, and to achieve mind boggling feats of breath hold (apnoea) duration. If you’re up to speed with my Physiology Bootcamp series, you’ll know that the main components of the Mammalian Dive Reflex (MDR) are:

Decreased Heart Rate (Bradycardia)

Decreased Flow of Blood to less critical parts (Peripheral Vasoconstriction)

Increased Flow of Blood to the Heart and Lungs (Blood Shift) and

Contraction of the Spleen

All of which help to make more oxygen available to the critical organs of the body: the heart, lungs and brain. Perhaps one of the less well known components of this reflex, however, is something called Immersion Diuresis which has far-reaching consequences for those of you who are, as it were, struggling to hold it all in:

The key organs for immersion diuresis are the kidneys, whose main function, as most of us know, is to filter the blood to remove waste products.

As well as this, however, one of the other critical functions of the kidneys is to control blood volume, not only in order to control blood pressure, but also the osmolality (that is, ’concentration’) of the blood.

The kidneys are amazing organs. Amongst other things they contain a mechanism for regulating their own blood flow, governed by a group of hormones, their effects and precursors called the Renin, Angiotensin, Aldosterone System. This system is triggered by a specialised group of cells in each nephron (the tiny filters inside the kidney) called the macula densa which effectively senses changes in blood flow to the kidney.

As the mammalian dive reflex is initiated, renal blood flow increases because of the “blood shift” - the redistribution of blood from the peripheries to the central organs. The macula densa detects this change as an increase in blood volume and acts through the Renin, Angiotensin Aldosterone system to increase urine output (known as diuresis) which is why you’ll find you need to pee more whilst you’re diving.

But what about that feeling of needing to pee as soon as you hit the water?

Why Does Water Make me Want to Pee?

There are two parts to the answer to this, and the first is quite similar to the answer above: When you hit the water, the hydrostatic pressure and the buoyancy effect cause an instant re-distribution of blood - pushing it from your legs and feet where it’s normally held by gravity, up towards the chest. This change is detected by the heart in the form of atrial stretch that is a stretching of the chambers of the heart caused by the increased blood flow to them. Atrial stretch causes a release of hormones called Atrial and Brain Natriuretic Peptide (ANP and BNP) which - guess what - affect the kidney, causing an increase in urine output.

That’s all very well, but often I find I need to pee almost the exact second I hit the water, sometimes even before that, and the mechanisms described above, although they act rapidly, seem to be too slow to really account for this. The solution probably lies in the psychological association between water and urination.

Those of you who’ve heard of Pavlov’s Dogs will know that it’s possible to train a physiological response (like salivation in the case of Pavlov’s original experiments) to occur in response to an arbitrary stimulus, like the ringing of a bell. Urination produces the sound of running water, flushing a toilet and washing your hands all produce sensations associated with wetness, that beautiful warm sense of release that comes as you give in and…wait, sorry? What?

Peeing in Your Wetsuit - The Personal and Social Perspective

So it’s official, there are a whole host of physiological reasons why it’s really difficult not to pee in your wetsuit (unless you want to take it off in the middle of a session, as some people do) but is it actually ok?! As an enthusiastic suit-pisser myself, I would have to say Yes! Absolutely! But am I a weirdo? Answers on a postcard please.

In my experience, the social acceptability of wetsuit-pissing varies from club to club. If you’re lucky enough to be surrounded by loose-bladdered companions then you’ll quickly adapt to the freedom and comfort that comes from “letting it all go”. If your buddies are a little more uptight, however, you’re going to have to keep a cork in it. Or lie.

One thing that’s definitely out, though, is pissing in someone else's suit. Freedivers are obviously close, but the smell of your ’s day-old piss in the crotch of your nice dry wetsuit is pretty much guaranteed to offend. In my book, if you’ve borrowed it, basically, you can’t piss in it, and if you do, you’d better have a backup plan. Jeye’s fluid, I hear, is pretty good, as is complete denial.

Let’s make one thing quite clear though. Unless you’re doing some sort of extreme “how long can I stay in the water” challenge, that horrible (presumably French) invention, the so-called “pissette" is absolutely not ok. However convenient they may be, however ‘manly’, however much they might improve your personal hygiene, no-one, absolutely No One needs to see that under any circumstances.

In conclusion, then, the problem is, to those of us in the know, pissing in your wetsuit just feels so goddam good. Can something that feels so right, so physiologically necessary really be wrong? I mean, you can always wash the thing afterwards, right? Isn’t that small uncertainty, that tiny little splinter of guilt that you feel just evidence of the tyranny of social expectation over the unassailable rights of the individual?

I’ll leave you with reflections on that very subject from one of my own personal existential heroes, the Muppets’ Miss Piggy, who offers proof that hidden within the small, everyday matters of life, deep philosophical questions lie buried. Who knew.

Join us again next week for more frolics in from Dr Otter and the Freedive-Earth team. Till then, have fun :) .