Sex in a pool. Why is it common enough to warrant a trope? Perhaps it's our distant amphibian past. Perhaps it's because you don't get cold. Perhaps water is an aphrodisiac. Perhaps the amount of glistening skin left exposed by bathing suits is a turn-on. Whatever, sometimes two people get into a swimming pool and take part in what many public pools describe as "heavy petting". Sometimes goes hand in hand with Underwater Kiss. Examples of Two-Person Pool Party include: