The Cavern of Doom is a section of the Great Underground Empire in the Eastlands that was rediscovered in the beginning of the tenth century after the defeat of Malifestro. This subterranean region, interlinked with the middle level of the Dungeon of Zork, included Grawl's residence, the Cavern of the Rainbow Mosses, the Crypt of Death, the Dungeon of Dry Bones, and the Hall of Mirrors.

It was in the Cavern of Rainbow Mosses were the cursed Logrumethar had been exiled to. When this section of the Great Underground Empire was rediscovered, adventurers and treasure hunters flocked into the vast new area. But none returned. Several knights went to search for the missing explorers, but they did not return either. For the cursed gaze of Logrumethar had turned them all to stone.

Syovar the Strong found that the entire region was guarded by some powerful enchantment. Wishing to prevent further disappearances, and with utmost reluctance, Syovar was forced to forbid access to that section of the Underground Empire forever. After sealing the door to the region with powerful magic, he left an inscription upon the door that read:

As ruler of the Kingdom of Zork, I hereby decree that this Cavern of Doom has been sealed off. No man may remove the spell that protects this door.

Syovar could only glean a vague feeling that the one able to enter the enchanted cavern and return was someone completely innocent and pure of heart. These were Bivotar and Juranda. Syovar opened up the region for the two adventurers, who were able to free Logrumethar from his curse.

Even though the curse was broken, the region is still referred to as the Cavern of Doom until this day.

SOURCE(S): Zork: The Cavern of Doom