the list
 

I too had completely forgotten volleyball - sungas and sometimes speedos are to be seen, particularly on Brazilian beaches (there is limited activity there also in beach wrestling).

Burning of the bum would not be a problem on a multiple waterslide I would think as the volume of water is a sufficient friction barrier. What might be a problem is the arms on the sides of a chute - need to tuck-in well on a narrow one.

Funny to think that hoisting the speedos is for the opposite purpose by the Aussie guys in their surf boat races.

Volleyball
 

I forgot to mention that the volleyball player I know said that while a very few US natives play in speedos to show off or intimidate the oppostion, speedos are more common on recent European immigrants.

old habits die hard
 

LOL - the French didn't invent the word le string for nothing.

Ill wear a speedo when Im doing my Kung Fu training outside.

It's not a sport, but Bikram Yoga is a great place to wear a Speedo.

It still is a great activity to wear one in... Ive wondered about speedos in volleyball. Why are the womens suits always riding up? When I see a gu in speedos playing he is always wearing a solar1 and it fits well but the womens suits are all over the place...

gender difference
 

Contours of the hips - the female body has to accommodate a womb.
The girls can simply pose well in their itsy bitsies but strenuous athletic
activity means they will not always remain as neat in their kit as the boys
can be.

And it is women who are considered normal and proper fit when wearing such garments lol... I love it anyway.

wrestling
 

A good sport for wearing a speedo/bikini is wrestling. If you have not seen movimuswrestling, then watch some of the matches, and I think you will agree. It is real wrestling (ok a little show), but it is real wrestling. And the guys, most of them look just fine. I've been to many matches in person. And the speedo assortment is amazing, I should know!

nice speedos