Once, when the moons were different it's said, the Melairkyn dwarves tunnelled under what would become Waterdeep. They disappeared, wiped out by the drow and duergar who invaded their halls in search of the dwarves' mithril. Ages passed, mighty Netheril fell, and a wizard came to live in the small fishing village of Waterdeep. His name was Halaster (though there's some dispute on this). As wizards do, he built a tower, and gathered apprentices.
What happened next is better documented: he delved below, into the realms of the drow, and embarked on a vicious slaughter of them, giving rise to the term "Halaster's Hunt", meaning a berserk massacre. His students apparently went below to find him, all save one, which is how we know what little we do...
Centuries passed, a millenia, and Waterdeep grew into a great metropolis. Durnan the Wanderer, a warrior of skill and courage, along with Mirt the Moneylender and others, found an old well shaft that lead into the subterranean world, they went down into Halaster's halls, and survived, returning with fame and riches! Soon, word spread, and more and more came to test their luck, and less and less left the halls below...

As Elminster so gracefully put it: "Undermountain? Ah, yes. A great place to have fun, the most famous battlefield in which to earn a reputation as a veteran adventurer --- and the largest known mass grave in Faerun today!"

The Physical Nature
of Undermountain
Traps Gates
Magic In Undermountain Dead Magic Zones Food Bins And Privvies
Rumours Known Areas Maps

THE PHYSICAL NATURE OF UNDERMOUNTAIN

Since a large portion of the place was carved from the living rock by the Melairkyn dwarves long ago, it holds to their regular, well crafted ways. Most corridors are 10' square, and the stout doors made of snug fitting stone. The doors are sometimes locked or trapped, though mostly by more recent inhabitants than the dwarves.
While the upper levels are a tad chill, the temperature increases with depth, so that by the third level it's quite warm. Here and there are grand halls and areas whos purposes are long forgotten, though their beauty and grandeur is unforgettable!

TRAPS

As any occupant would, those who live in Undermountain defend their homes as best they can, thus traps are not at all uncommon. In the more travelled areas, naturally, they tend to be rarer, as they are frequently cleared. The older traps tend to be the most deadly, left by the Melairkyn dwarves or Halaster, these nightmares of devious destruction are woefully efficient and murderous!

GATES

Magical areas designed to link two places together, these are not the same as Teleports (which rarely work, see below). Some gates bring fresh air into the dungeon, others food or creatures. A rare few are entrances people may use to access other levels in the labyrinth, or even other Planes! Gates are generally invisible, and may have odd effects on travellers. Note that some are "portals" to other Neverwinter Nights games.

MAGIC IN UNDERMOUNTAIN

Some spells and similar abilities do not fuinction correctly in Undermountain, this is believed to be due to the many spells Halaster cast in and on his labyrinthian home. It is important to note that Teleport and related spells, like Dimension Door, Succor and Word of Recall do not function in Undermountain, except for very short distances! However, Phase Door and similar natural abilities still work. Teleport moves things from place to place, Gates make their spacial areas congrous (at least that's what wizards say!), and thus the magical weaves made by Halaster interfere with Teleporting. Conjuration/summoning spells work more or less normally, as Planar access isn't restricted, and there are many monsters in Undermountain to summon. Another problem is that these "weaves" also block spells that try to pass through the walls or doors, such as using a Locate Object to find a key in another room. Also, due to the pervasive magical fields, Detect Magic is not reliable, since it's often "swamped" with mystic emanations.

DEAD MAGIC ZONES

There are a few of these deceptively dangerous zones scattered here and there. No magic what so ever will function in these places! The effect is as if an Anti-Magic Shell had been cast. Normally dead magic zones are not so powerful, merely stopping the ability for spells to be cast, but thanks to Halaster's experimentations with arcane forces, magic simply will not work in these places. Spellcasters and magical creatures can sense such areas and avoid them like the plague. More mundane folk, however, see the use in being invulnerable to magical detection or assault...

FOOD BINS AND PRIVVIES

One of the odder things about Undermountain, is that scattered here and there are privvies, these simple toilets keep the place clean. So they were probably placed there by the halls' dwarven builders, but, near them you will always find a "food bin". These are like a large rectangular cupboard carved in the wall, with 3 troughs that are filled now and then with water, some vegetable-type food (fungi perhaps?), and meat. These items appear magically and at irregular intervals. It is believed that these were placed by Halaster to feed his servant creatures. Now they are highly prized, since food is scarce in Undermountain (apart from the two legged kind), and many monsters set up their lairs around such a valuable commodity.

RUMOURS

If there's one thing that Undermountain has no lack of (apart from danger), it's rumours! All kinds of stories are told of the place, from the mundane to the preposterous. Here are but a few of them:

KNOWN AREAS AND THINGS OF INTEREST

A few places and oddities have become well known to explorers of Undermountain:

MAPS

As heroes delve into the labyrinth, they create maps for others to follow. And some of the folk in the Yawning Portal may sell or give maps to adventurers. Players in these games are free to create maps of areas they have explored, and I will either post them here, or put them in the game itself! So if you make a map, SIGN it! It's your footnote n the history of Undermountain! The following is a simple map, it shows some well known features around the entrance area from the yawning Portal, characters will be able to learn such things easily from tales etc, so it is appropriate for everyone to see.

  1. Map 1 The entrance from The Yawning Portal