Hylas in Jason and the Golden Fleece
Hylas was a prince of the Dryopians and companion to Heracles. Many say that the young man was also Heracles' lover, making the boy a lot like Iolaus, Heracles' other famous eromenos (boy-lover). While on the quest for the Golden Fleece, Hylas is seduced by some water nymphs and taken to live forever beneath the waves.