
1) Location in Greek mythology
Found on
https://www.crosswordclues.com/clue/acherusia

In Greek mythology, Acherusia (`Αχερουσια λιμνη or `Αχερουσις), was a name given by the ancients to several lakes or swamps, which, like the various rivers called Acheron, were at some time believed to be connected with the lower world, until at last the Acherusia came to be considered to be in the lower world itself. The .....
Found on
http://en.wikipedia.org/wiki/Acherusia

In Greek mythology, Acherusia was a cave on the borders of Pontus which led to the infernal regions. It was through this cave that Hercules dragged Cerberus to earth.
Found on
http://www.probertencyclopaedia.com/browse/D1A.HTM
No exact match found.