The Lake of Acid, known to the Dark Elf as lanke de' ussvelusscal, was a pit in the highest reaches of the Underdark where several natural tunnels met. A few days journey in the Upperdark from the opening of Giantsbane, the "lake" was in truth filled with extremely powerful acid, which could melt the flesh off a creature with nearly the potency of lava. It was unknown how this acid came to be, and various myths and legends were theorized by different Underdark races. The lake seemed to be self-replenishing, however; its acidic contents dripped ceaselessly from above, creating extremely precious and unique gemstones in the surrounding caves as well below the lake's grounds.
These precious stones, as well as the pillars holding up the Lake of Acid, attracted the attention of Dark Dwarf, who mined the location to near-instability. Several stone bridges connected the tunnels over the lake, at various heights, long ago constructed by the duergar who forged them. Many of these tunnels fell into disrepair during the countless battles that were fought after to control the territory. The nearby tunnels with claims to the area included Grell, Intellect Devourers, and Driders leading battalions of Giant Spiders; the reasons for these claims were inscrutable. Cave Fishers and Ropers often hunted here, but did not linger for long.
At the lake's northern edge was a set of heavy stone doors the blocked off the exit to the surface world in the southern Crowncrest Mountains. Carved into these doors was a visage of Silver Dragon, with a hidden keyhole in its eye; past it was the Silver Dragon's Hideout.