The second task of Hercules was to destroy a hydra or water snake
which dwelt in the marsh of Lerna, a small lake near Mycenae. The
body of this snake was large and from its body sprang nine heads.
Eight of these heads were mortal, but the ninth head was undying.

Hercules stepped into his chariot and his dear nephew Iolaus, who
was permitted by the Delphic priestess to drive for him, took up the
reins. The way to Lerna was pleasant. In spring-time crocuses and
hyacinths sprang by the roadside, and in early summer the
nightingales sang in the olive groves, vineyard and forest. That so
great and horrible a monster could be near!

When Hercules and Iolaus came to Lerna they drew close to ground
rising near a spring, and Hercules dismounting and searching found
the very hole into which the hydra had retired. Into this he shot
fiery arrows. The arrows discomforting the snake it crawled forth
and, darting at him furiously, endeavoured to twine itself about his
legs. The hero began then to wield his mighty club. He crushed head
after head upon the snake's body, but for every one crushed two
sprang in its place.

At length the hydra had coiled so firmly round one leg, that
Hercules could not move an inch from the spot. And now an enormous
crab came from the water out of friendship for the hydra, and that
too crept up to Hercules and, seizing his foot, painfully wounded
him.

Swinging his club with heroic vigor Hercules beat the crab to death.
Then he called to Iolaus to fire a little grove of trees near by.