I visited Rio's in London one Friday night a couple of years ago. From what I've read, it hasn't changed much since then.
Rio's is a "naturist" club, everyone in towels only. They have a pretty ok place, a few hot tubs a quite large, a sauna & hamman, pool & private rooms where you can close the door to play. There were a number of single male/female & an equal number of couples, age ~low 20's to 60's, maybe 50 or so people between 20:30 & & 1:00. Some quite ordinary & quite lovely too, all friendly. I saw a little play in the large hot tub between a couple & a singe girl, then they moved to a private room. Other than that, I didn't see any other action. I'd visit again though if I have a chance.
