This wretched swamp is south of Mizzen and east of Vorkrak. It is a foul place inhabited by blood mosquito swarms, will-o-wisps, crimson deaths, trolls, muckdwellers, green hags, hydras, and undead. Skeletons, zombies, ghouls and other foul undead roam the fetid swamp called Nelthack. These creatures are creations of something even more foul in the area. They are a product of a Wraith Queen named Belgunth.
At the northern edge of the swamp is Sakullêth. This ancient city was built by the yuan-ti of Mizhint.