Out of the Abyss
Though its name might evoke images of a single subterranean body of water, the Darklake is a network of underground rivers, natural tunnels, and canals that connect innumerable water-filled caverns and chambers. This vast waterway stretches over a hundred miles across, with ceilings that are miles high in some places and depths that are unfathomable.
Long ago, duergar engineers extended and widened many of the interconnecting passages of the Darklake. They also constructed locks for raising and lowering watercraft to different levels within it, opening up large portions of the network for travel. Many Underdark creatures are experienced in navigating the Darklake, including the kuo-toa – fishlike humanoids known for their insane obsession with unraveling the secret patterns of the Underdark. Still, better to trust a kuo-toa guide than attempt to traverse the Darklake alone and become lost within it forever.
You can use the Darklake to reach many destinations in the Underdark. More importantly, water travel makes it difficult for your drow pursuers to track you. The kuo-toa town of Sloobludop is located on the eastern edge of the Darklake, and is a potential source of watercraft and navigational aid. But as you seek out these resources, you learn of terrible powers loose in the Underdark – worse than the drow, the kuo-toa, or any other threat of this dark realm.