[Twisol]

Except for the gross factor? The author seems pretty clear that, yes, you can:

> For those of you asking, what are my options for diving in a dry suit? Well… you can just hold it (again, if you have a bladder of steel), nappies/diapers, the p-valve, or just pee in the suit (which is gross and defeats the whole purpose of the dry suit, right?).

The "purpose of the dry suit" is to keep you dry. If you're literally wetting yourself, and with a fluid that is rather more chemically offensive than water, then you're probably going to have a bad time. (I don't know how temperature-controlled dry suits are, but you lose heat a lot more easily through contact with a liquid (that's what sweat is for!), so the urine puddle probably makes heat retention harder, too.)

[hinkley]

I live where the water barely gets warm enough to swim in during the summer, so kayaking is often a dry suit activity. When I was taking a class I had quite a time staying cool. Some people flip on purpose, or you just shove as much of an arm into the water as you can and wait. A dry suit makes 50°F water feel like a crisp morning with still air, instead of torture.

Water inside reduces that insulation. I wore my synthetic base layers underneath just in case.