These marshes form a natural border between Keoland and the Hold of the Sea Princes to the south. Surprisingly this wetland is a hotbed of published adventures. The sequels to Saltmarsh, U2: Danger at Dunwater and U3: The Final Enemy are set here. For more scaly threats, the generic AD&D module I2: Tomb of the Lizard King was retroactively placed in Keoland in the County of Eor. And lastly, another generic adventure, I7: Baltron's Beacon can be found in the depths of the Hool Marsh, its ghastly green glow a warning to foolish heroes. Beyond these published modules, the Hool is a vast tract of swamp that can support hidden cults, bandit hideouts and other abandoned edifices from past imperial expansions.