Cocytus

[1] Cocytus flows into the river Acheron, on the other side of which lies Hades, the underworld, the mythological abode of the dead.

"[4] In Inferno, the first cantica of Dante's Divine Comedy, Cocytus (or Treachery) is the ninth and lowest circle of The Underworld.

Cocytus is divided into four descending "rounds", or sections: Dante's Satan is at the center of the circle buried waist-high in ice.

Under each chin, Satan flaps a pair of wings, which only serve to increase the cold winds in Cocytus and further imprison him and other traitors.

Though Dante is initially confused as to why they are turning round, Virgil explains it is due to the change in forces as they pass through the center of the Earth.