Acherusia

In Greek mythology, Acherusia, a name given by the ancients to several lakes or swamps, which, like the various rivers of the name of 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 lake to which this belief seems to have been first attached was the Acherusia in Thesprotia, through which the river Acheron flowed. Other lakes or swamps of the same name, and believed to be in connection with the lower world, were near Hermione in Argolis, near Heraclea in Bithynia, between Cumae and cape Misenum in Campania, and lastly in Egypt, near Memphis.

In Greek mythology, it was the name of an underground cavern, through which Heracles dragged Cerberus as one of his Twelve Labors.