The Charon River is a mythical river in Greek mythology. It is said to be the river that separates the world of the living from the underworld. The two rivers that make up the Charon River are the Acheron and the Styx. The Acheron is a river of woe, and it is seven letters long. The Styx is a river of hatred, and it is four letters long. Together, they form the Charon River, which is the boundary between the world of the living and the underworld.