Nectar

Nectar was called the divine drink that the Olympian gods had. It had the magical property to confer immortality on any mortal who had the luck to drink it. It was closely related to ambrosia, which was considered the food of the gods, although sometimes it was also thought to be a drink. It was a grave offense to steal either nectar or ambrosia. Tantalus tried to steal ambrosia from the gods, and this condemned him to an afterlife in the Underworld where he was eternally punished to suffer of hunger and thirst; he was forced to stand in a river, but any time he would try to drink water, the waters would recede. Similarly, when he tried to reach the branches with fruit that were above him, they would also move further away from him.

See Also: Ambrosia, Tantalus