The Underground

First Visit [L. 40-41]
The Underground is a huge network of tunnels and caverns which change depending on the tide. Lolth created her nest here to due to the natural defense system it has. Working as a nearly-impenetrable fortress, Lolth chose well.
 * Death's Door
 * The Labyrinth
 * Gezeiten Stadt (Hall of Spiders, Muted Wall)
 * The Frostshear
 * Fafnir's Litany

Second Visit [L.46]

 * The Mute Reef
 * Fafnir's Mead Hall
 * Lolth's Well