They unzip down the front. Yes, if you lack a penis you'd have to get your arms and butt out to urinate, but that's hardly the same level of challenge as having

They unzip down the front. Yes, if you lack a penis you'd have to get your arms and butt out to urinate, but that's hardly the same level of challenge as having to end a dive, surface, undo all your seals, and then get your arms and butt out of a drysuit.