If it hasn't happened to you already, it will. You descend to 15 feet, and you'll feel the sudden urge. You can't hold it. And there's no way you can get to a bathroom without spoiling the whole dive. So you consider - if I'm in the water, my urine will just dissipate and dissolve and disappear. Is it OK to whiz in the wetsuit?

The simple answer is "yes". Take a leak.

The truth is, there is no health risk to watering the neoprene. Many people do not realize that urine - unlike feces - is sterile, unless you have a urinary tract infection. It contains a lot of dissolved bodily waste (mainly nitrates), but poses no health risk to you. The only symptom of wetsuit whizzing is temporary warmth in your vicinity. But beware, if your urine is dark (a sign that it is probably strongly odorous as well), you might get a reaction from other divers, especially if they happen to swim through your "yellowish cloud of warmth."

As a frequent diver, your best strategy for dealing with this common situation is counterintuitive: drink more water. A hydrated diver can urinate in their wetsuit and their urine will not be dark or smelly. You have surely noticed the difference between your morning pee and your pee after (or during) a long night of drinking. Dehydration is very common, yet minimal dehydration is tolerated and goes unnoticed by most people because of the symptoms are fairly mild. If you are properly hydrated, your urine is clear and odorless. A practical diver should drink plenty of fluids the night before and the morning of a dive, to ensure adequate hydration.

You may hear divers joke about "warming the wetsuit". The warmth offered by wetsuit irrigation is comfortable, but temporary. Yes, when you pee you will feel warm initially, but in the end it will actually lower your overall body temperature.

You might notice that even though you relieved yourself before the dive, you need to go again when you get down to 20 feet. Why do you need to pee again? You may be experiencing a phenomenon called immersion duiresis: as a response to an increase in pressure, your body feels compressed and your kidneys start to produce urine.

Since you already rinse your wetsuit after each dive, you don't need to be concerned about odor from your underwater urine. An unrinsed wetsuit develops its lovely stink from algae and crud in the water, not from your urine. Tinkle away!