Alcyonian Lake (al-cee-OH-nee-an). Bottomless lake. In the vicinity, or perhaps even part of the swamps of Lerna in which Heracles fought the Hydra. The wine-god Dionysus used the Alcyonian Lake as a portal to Hades when he rescued his mother Semele from the Underworld. The heroine had died in a bolt of lightning when she asked Zeus to reveal to her his true nature as storm god. To retrieve her from the Underworld, Dionysus went to Lerna and dove into the fathomless lake.