The term 'River in Hades' refers to three rivers in Greek mythology that are located in the underworld. The first river is the LETHE, which is a river of forgetfulness and oblivion. The second river is the Styx, which is a river of hatred and unbreakable oaths. The third river is the Acheron, which is a river of pain and sorrow. All three rivers are located in the underworld, also known as Hades.