Styx

The Styx (Greek: Στύξ, Stux, also meaning "hate" and "detestation") (adjectival form: Stygian, play /ˈstɪdʒi.ən/) was a river in Greek mythology that formed the boundary between Earth and the Underworld (often called Hades which is also the name of this domain's ruler). It circles the Underworld nine times. The rivers Styx, Phlegethon, Acheron, and Cocytus all converge at the center of the underworld on a great marsh, which is also sometimes called the Styx. The other important rivers of the underworld are Lethe and Eridanos, and Alpheus.