The Fountain of Youth, or the Agua de Vida (among numerous others), is a legendary spring which will reputedly grant youth and immortality to anybody who drinks from it, at a price, but it's not a question of simply quaffing. The two Chalices of Ponce De León must be retrieved and a Mermaid's Tear acquired, then fill both chalices and drop the Mermaid's Tear into one. The drinker from the tearless chalice will receive life from the lachrymose drinker... Good luck on that quest, for ye'll have uttermost need it.