Cocytus, also known as Kokytos ("lamentation"), is the river of wailing in the underworld in Greek mythology. Cocytus flows into the river Acheron, and on the other side lies Hades, the underworld. There are five rivers encircling Hades: the Styx, Phlegethon, Lethe, Acheron and Cocytus.
In Inferno, the first cantica of Dante's Divine Comedy, Cocytus makes up the majority of the ninth and lowest circle of The Underworld, Treachery. Cocytus is referred to as a frozen lake rather than a river, although it originates from the same source as the other infernal rivers, the tears of a statue called The Old Man of Crete which represents the sins of humanity. Dante describes Treachery as being the home of traitors and those who committed acts of complex fraud. Depending on the form of their treachery, inhabitants are buried in the frozen lake of Cocytus to a varying degree, anywhere from neck-high to completely submerged.
Cocytus also makes an appearance in John Milton's epic poem Paradise Lost.
