Depth - an unexplored caving system beneath the mountains of the land of Eketh, probably reaching down to the center of the earth. It is inhabited by mysterious creatures called Nightmares. After the Miners in the Horned Mine dug into the Depth, Nightmares began to appear in the mine, which led to it getting closed. Eketh rulers tried to exterminate them - they sent the army, heroes, but failed. In the end, the Horned Mine was closed.