Vast Swamp

The Vast Swamp was an area of swampland in interior Faerûn that lay between Cormyr to its west and Sembia to its east. It was widely thought of as the most dangerous stretch of wilderness in the land. Ignored by surrounding nations, it had no proper name; "vast swamp" appears to be a nickname that stuck.

Geography
It was flanked to the north and east by the Thunder Peaks mountains, to the west by the Eastern Plains of Cormyr, and to the south by the Dragonmere, a body of water that poured into the Sea of Fallen Stars. Between the swamp and the coast ran the Way of the Manticore, the only overland route between Cormyr and Sembia.

The Vast Swamp was largely marshland covered with forest of middling density, making it appear more like a flooded forest than an actual swamp. One could rarely see far for the forest. The terrain was dominated by undergrowth and bogs with precious little clear, dry land to be found anywhere within its borders. The ground underfoot was soft and spongy, largely comprising thick peat. What paths there were to be found winding through the swamp were little more than muddy trails.

The many deadly natural hazards of the swamp included insects that transmitted diseases, noxious clouds of gases, dense fogs that were utterly impenetrable, patches of quicksand and bogs that would suck the unwary down to their doom, and the freezing rain that fell thereabouts.

The borders of the swamp were forever expanding towards the Way of the Manticore, slowly but inexorably. When it finally reached the road, it might halt all overland travel between Sembia and Cormyr.

Climate
Whether in the depths of winter or the height of summer, the marsh and forest were forever shrouded with a murky fog. Even in bright sun, the entire swamp was coated with a thin and persistent mist, making it hard to see more than a mile (1.6 kilometers) in any direction, even if one could see over or past the trees. Even fog from the Dragonmere coast constantly rolled inland towards the swamp.

Geographical features
The Vast Swamp was the source of the Darkflow, a river that flowed from the center of the marsh and south into the Lake of Dragons.

Flora
Around the fringes of the swamp grew blueleafs and oak, typically gnarled and stunted. As one ventured further in, copses of more tangled trees grew more common and finally became predominant. A variety of trees grew in the heart of the flooded forest: black gum, cypress, water ash, water birch, and willow and weeping willow. These invariably choked the region and were draped in moss. Meanwhile, duckweed floated on the waters.

Politics
The Vast Swamp and the Darkflow served as the de facto border between the realms of Cormyr and Sembia, largely because neither Cormyr nor Sembia had any interest in laying claim to the land, nor anything beyond. The myriad of monsters and other hazards made the Vast Swamp the most dangerous place in either land, people had no cause or desire to go in, and clearing it and draining it would be an epic undertaking, so both nations were happy to ignore it—at least until some raider or monster crept out and into their lands.

Thankfully, the savage denizens of the Vast Swamp usually stayed in its confines, content to war between themselves rather than raid the neighboring lands.

Nevertheless, the Vast Swamp enticed explorers who would brave the dangers and endure the difficult environment. However, neither Cormyr nor Sembia themselves had attempted any major expeditions into the Vast Swamp before the late 14th century DR. Hence few people knew for sure what lurked in the darkest, dankest depths of the swamp.

History
In the Year of the Thirsty Sword, 900 DR, King Galaghard III's army, the Glory of Cormyr, drove the Witch Lords and their undead forces toward the Vast Swamp. They caught and trapped them there against the swamp's western shore and finally defeated them.

In the Year of the Dragon, 1352 DR, the Lost King Gondegal, who attempted to carve his own kingdom out of Cormyr, extended his reach as far east as the Vast Swamp.

The Skull Staff
Just within the swamp on its south-western border was a 30' high log jutting out of the ground at a steep angle. Its base was surrounded by a many and varied number of skulls and more lined its sides, held in place by spikes and wooden stakes. It was constructed in 1274 DR by an orc tribe to warn other creatures away from their territory. When they were chased from that land, its new occupants used it for the same purpose, adding the orcs' skulls to it. It was adorned with skulls of orcs, goblins, hobgoblins, trolls, lizardfolk, crocodiles, hydras, and dire boars. In 1374 DR, it was under the control of the Shadowscale lizardfolk tribe, who felled trees to make a muddy path for their Sharran allies to take ensorcelled magic-users to the Lost Refuge.

The Lost Refuge
The Lost Refuge was a Cormyrean keep placed near the border of the Vast Swamp. It supported a town as well but nearly a hundred years ago the combination of the expanding swamp and an orc attack killed the garrison and Cormyreans subsequently forgot all about the place. It was shortly thereafter conquered by hobgoblins but more recently fell into the hands of Sharran cultists. Legend has it that the Dusk Lord of Sessrendale opened up a planar rift to the Plane of Shadow in this keep after fleeing from his former homeland.

Orvaskyte Keep
Sages agreed that Orvaskyte Keep, discovered in the 1360s DR by adventurers seeking missing comrades in the swamp, was built by members of the kingdom of Orva. The keep was believed to have been built around the 7th century before Dalereckoning, but was reported to be (in 1374 DR) occupied by fiends and other monsters, which abruptly ended all considerations of exploring the place further.

Elven ruins
Many years before 1374 DR, an adventuring group called Moon's Twelve went into the Vast Swamp looking to find their fortune. The last surviving member, Sylara, returned to civilized lands ranting and delirious about an elven ruin as extensive as Myth Drannor but her group was run off by mind flayers and beholders. She died of a swamp fever before she could elaborate further and no one knew if what she saw actually existed.

Inhabitants
The Vast Swamp was known to be heavily populated by tribes of lizardfolk, hobgoblins and other goblinoids, orcs, gnolls, and trolls. There were also reports of catoblepas, a few black dragons (mostly small), one or two insane beholders,  occasionally hydras, and even grell, as well as stories of even stranger monsters.

Will-o'-wisps were also found there, and were often sighted from the Way of the Manticore.

Meazels were widespread in the Vast Swamp. They regularly preyed upon kobolds and goblins they could catch alone.

Rumors and legends
According to one legend, the notorious Dusk Lord of Sessrendale was not killed as history recorded, but instead escaped into the Vast Swamp. There, the story said, he plotted vengeance against all living beings in the Dalelands. The Dusk Lord was the most well know of the villains said to inhabit this land.

There were rumors of mind flayers, beholders, and lichs lurking in an ancient ruin close to the center of the marsh. Necromancers were also reputed to make their homes in the Vast Swamp. Evil magic was said to lay about the swamp, and the dead were restless.