The Dungeon of Dry Bones is an underground cavity near the Cavern of Doom region, the only entrance being through a trapdoor in the floor of the tunnel above which many careless adventurers have fallen through. When a thin beam, which crosses the tunnel at a certain place, is broken, the floor gives way to an incredibly long shaft that connects to the dungeon. Starvation is the most commonly used method of escaping from this forbidden pit filled with bones.

SOURCE(S): Zork: The Cavern of Doom