The Hydra of Lerna was killed by Heracles as one of his Twelve Labours. Its lair was the lake of Lerna in the Argolid, though archaeology has borne out the myth that the sacred site was older even than the Mycenaean city of Argos, for Lerna was the site of the myth of the Danaids. Beneath the waters was an entrance to the Underworld, and the Hydra was its guardian.In Greek mythology, The Lernaean Hydra was a snake-like beast that possessed nine (usually nine, it ranged from five to one hundred) heads and poisonous breath, killed by Heracles as one of his Twelve Labours.
The Hydra was the offspring of Typhon and Echidna, noisome creatures of the Goddess who became Hera. It was said to be the sibling of the Nemean Lion, the Chimaera and Cerberus. As such, it was said to have been chosen as a task for Heracles so that Heracles would probably die. (Source: mlahanas.de)
