Darklake

The Darklake is actually a series of flooded caves connected by short, sloped tunnels. Some portions of its area are vast and open, spanning dozens of miles at a stretch, but the whole of the lake is more than 100 miles across and 2 miles from top to bottom. Thousands of years ago, the duergar of Gracklstugh widened many of the tunnels and built a series of locks into them, allowing all the caverns to be traversed by large, shallow-keel boats.
Because of its proximity to Gracklstugh, Mantol-Derith, and Menzoberranzan, the Darklake has become a highway for trade in the area. The duergar city of Gracklstugh sits on the southwest shore of the Darklake. Menzoberranzan lies about 30 miles north of it and about 2 miles above, but several well traveled paths descend from the City of Spiders to the lake's shores.
The Darklake gets its name from the unnatural darkness of its waters. Magical light sources cannot penetrate its depths to more than 10 feet, and even darkvision doesn't help. The ceiling above the lake is generally about 30 feet above the waterline, although in some caves the ceiling is as high as 300 feet, and in others it hangs as low as 5 feet.
A number of Kuo-Toas run a ferry service around the Darklake, primarily between Gracklstugh and ports near Menzoberranzan. They also put in at other ports in the Deepkingdom and make infrequent stops around the edges of the lake near inhabited areas. No one knows where these kuo-toas come from, but their service is reliable and reasonably priced, and they avoid becoming entangled in events that are not their business.

Type

Lake

Location under

The Underdark