Wetlook World Forum

Then again, some have argued that as more and more girls do wear a bikini top as regular underwear, it is now pretty much normal clothing. But I would still imagine that this is normally for when they think they might get wet...

As for why swimwear under normal clothes? My own guesses: Skin and swimwear dries faster than regular clothing; if you are wearing a bra or no underwear, you cannot take off your cold, wet top as you'd be in your bra (which may be translucent) or half-naked. It gives you more options as you can remove your to swim properly with less drag in the water. Or to tan. All without looking indecent.

There's nothing unnatural or bad about it, sadly, no blame we can place on any girls ... But sadly it just doesn't match what we want to see.