The vast stretches of fens and bogs north of the Howling Hills separate Blackmoor from the lands of the Wolf Nomads and the Rovers of the Barrens. Here rise the Dulsi and Opicm Rivers, both of which feed the great Whyestil Lake. There are said to be riches in the highlands to the south of the marsh, but only the very brave or extremely foolish venture near the place, for the Cold Marshes are most renowned for the vile creatures which inhabit their mires.
The vee of land, which narrows to, but 30 leagues in breadth above the neck of the Tilvanot Peninsula is sunken in the center and cliffed along both coasts. This cupping causes water to form into standing pools and sluggish streams and flowages. The resulting morass of water and vegetation is known as the Vast Swamp. The upper swamps begin below the middle of the Hollow and Hestmark Highlands, which flank it to west and east. The swamp runs southward for well in excess of 200 miles, being over 150 miles across at the top and funneling down to only 30 miles breadth at the base where Spine Ridge rises. The movement of water in the Vast Swamp indicates that it gradually drains southward, hut there is no known river rising from the end, so it is thought that there are underground channels through which the waters run.
Certain desperate outlaws dwell within the Vast Swamp, and there are also native humans and humanoid tribes, bullywugs in particular, found within its bounds. Ferocious predators and loathsome monsters likewise consider this their domain. The men of Sunndi, and the folk dwelling in the hills to either hand, keep constant watch to assure that these denizens of the Vast Swamp do not roam beyond its edges. There are many tales and legends concerning this area, but the most likely is that of the lost burial place of the demi-lich, Acererak, who once ruled the morass and beyond into the cockscomb of Tilvanot.
Gnatmarsh: This comprises an extensive area of very treacherous wetlands which stretch along the east hank of the Nesser River from the Celadon Forest to below the joining of the Duntide. These bogs are home to many ghastly creatures and spawn myriad millions of biting insects during the summer months.
Hool Marshes: After the initial rush of the Hool River from the high lake and freshets in the Hellfurnaces, it begins to meander across the plains, and most of its length is surrounded by quaking mires and bottomless pools. This forms a natural boundary between the lands of the Yeomanry and the holdings of the Sea Princes to the south. These marshes are also home to renegade humans, humanoids, and many types of monsters.
Lone Heath: This great marsh gives rise to Mikar River east of the mighty Grandwood Forest. The area provides sanctuary to outlaw humans and demi-humans fighting the evil and oppression of the Over-king and his minions. Unlike most areas of this sort, evil things fear to enter the trackless Lone Heath.
Pelisso Swamps: These unhealthy stretches along the north coast of Hepmonaland are unexplored and who or what dwells there is unknown.
Rushmoor (Marshes): A long stretch of land east of the mid-Javan to the headwaters of the Sheldomar is known as the Rushmoors. This area forms part of the northern boundary of Keoland and is a part of the unclaimed region consisting of the central Dim Forest, eastern Oytwood, and the Rushmoors. Many dangerous creatures inhabit the marshes, and there are reports of humanoid bands there as well.
Troll Fens: The chill mists of the Troll Fens, located against the shoulders of the Griff Mountains and the Rakers at the head of the Yol River, cloak a place of unnameable horrors. The Pale carefully hedges the place with watchtowers and keeps, and strong patrols constantly ride the verges of the southern end of the Troll Fens to watch for unwelcome visits from the monsters and humanoid bands dwelling within. As its name implies, the fens are infested with particularly huge and vicious trolls in numbers.