The Underworld also features four other waterways: Acheron, the river of woe; Cocytus, river of wailing; Lethe, river of oblivion; and Phlegethon, river of fire, a great source of natural light.
But we might recall that the Gorgias also ended with a discussion of the afterlife and the judgment accorded to the virtuous and the vicious in Hades, where the unjust receive a slap in the face for eternity.