In Greek mythology, "the River Styx" (Στυξ) is a river which formed the boundary between Earth and the Underworld, Hades. It circles Hades nine times. The rivers Styx, Phlegethon, Acheron and Cocytus all converge at the center of Hades on a great marsh. The other important rivers of Hades are Lethe and Eridanos. Styx is guarded by Phlegyas, who passes the souls from one side to another of the river. In other versions, Phlegyas guards Phlegethon, another of the main rivers of Hades. Sometimes the ferryman is called Charon.
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