The darkest and most remote corner of the Stone Tooth's cavern system, the Black Lake was a large, winding cavern. It filled with water that drained from a mire in the Forest of Stone Tooth on the mountain's east side via a submerged siphon. The waters within were pooled from the upper floors of the Foundry and the lower Sinkhole of Khundrukar, and the cave was dotted with many foreboding stalactites and stalagmites. Two stone bridges lead to a back entrance to the foundry, accessible by ascending a 120-foot ladder made of steel chain and brass.
Though mostly unoccupied save as a back entrance to the foundry, a young Black Dragon named Zyrmintyl occupied one of the lake's small islands around 90 AD. There, she developed a minor dragon horde from treasures that floated from Khundrukar, as well as from the Troglodytes who worshipped her from the Glitterhame.