Acheron
ACHERON (River of Sadness) In Greek mythology, the “woeful river” of the UNDERWORLD into which flowed the Phlegethon and the Coctyus. Acheron was the son of GAIA. He had quenched the thirst of the TITANS during their war with ZEUS, who then changed Acheron into a river. To cross the river Acheron, it was necessary to seek the help of CHARON, the ancient ferryman of the underworld. Acheron is sometimes used as a synonym for HADES, the underworld.
Taken from : Greek and Roman Mythology A to Z, Revised Edition – Written by Kathleen N. Daly and Revised by Marian Rengel – Copyright © 2004, 1992 by Kathleen N. Daly