The Great River of Acheron is one of the many rivers in the realm of Hades. The river's surface is black and boiling—not muddy, but something more like the total absence of anything in the water that might sustain life for any creature that had ever lived. The water has been said to reek of the foulest stench any man has ever smelled, it stung fiercely when it splashed against human skin, and the taste was enough to make one vomit. The Acheron incessantly booms and roars as if it were falling from immense heights.

This black, fuming flow is one of at least two rivers which the Hades Shuttle Service ferries new lost souls across (the other being the Styx) for their eternal damnation. The crossing of this river is done from the Dungeon of Zork entrance.

SOURCE(S): The Zork Chronicles, Zork Grand Inquisitor,  Zork I