Problem with swimming nude is once you get used to being that way all the time, it's pretty hard to go back to being comfy in clothes.
Speedos are fine when necessary, keeps everything in place nicely. But those baggy trunks...eewww. All that drippy water running down your legs when you get out, the feel of that cold wet clingy material against your skin...brrrr... gives me the willies just thinking of it.
After swimming sans clothing, one comes to wonder what asshole ever thought up the idea of swimming in clothes in the first place.