The Gwragedd Annwn are faeries from Wales, and live in lakes in underground towns. They are generally seen as female and like to marry mortal men. A Welsh legend says that on New Year's morning, a rock near an inhabited lake would temporarily sport a door, which would lead to an island in the middle of the lake if opened. A mortal brave enough to enter would be rewarded by festivities and food and music, and they would be entrusted with the secret of the faerie island.