Acheron: The River of Woe snakes through Propylaia, and serves as the boundary line between Propylaia and the Ony Towers.
Coxytus: The River of Lamentation is located on the western side of the Underworld. Emerging from Oceanus, it consolidates with the Lethe and Acheron towards the Onyx Towers.
Kokytos: The River of Tears lies in the far eastern section of the Onyx Towers. Not to be confused with the Coxytus, this river leads to the entrance of the Tartarus Pits.
Lethe: The River of Oblivion is located on the western edges of the Underworld. It forms the Mnemosyne, the waters of memory, where it blends with the Coxytus. Shades often drink from it, to help them forget sorrows of their mortal life with the hopes of a reincarnation.
Pyriphlegethon: The River of Flame is situated in the southeast, and is the main path to the Tartarus Correctional Facility.
Styx: The River of Hate is located to the east of the Mourning Plains, separating the entrances to Tartarus from the rest of the Onyx Towers.