葉月 said: Isn't it only cut/folded in the front to allow, well, whatever is the function of that thing?
There is a hole of sorts in the front to allow water to pass through, reducing resistance, as water flows in from the chest area as they swim. Supposedly.
School swimsuit is a one-piece, but yeah, like the above posters said there's hole in the front to let water pass through for, har, less water resistance.