I’ll use this page to post common knowledge about Undermountain. Please note that anything posted here could be true, completely false or somewhere between those extremes.

I plan to incorporate much of the established background information about Undermountain spelled out in the third-edition book Expedition to Undermountain as well as both second-edition boxed sets related to Undermountain and a slew of second-edition modules. However, while I’m using those sources for ideas, you should not consider anything official unless it’s posted here (in which case it might not even be true).

Here is what you think you know:

  • Undermountain was built by dwarves more than 2,500 years ago (-1288). It has in turn been captured and ruled by various races, including drow, throughout its history until the year 168, when Halaster Blackcloak (sometimes called the Mad Mage of Undermountain) and his seven apprentices (Arcturia, Jhesiyra Kestellharp, Muiral the Mishapen, Nester, Marambra Nyghtsteel, Rantantar and Trobriand) descended into its halls. By 309, Halaster and his apprentices had brutally exterminated the drow and duergar and ruled Undermountain.
  • Halaster’s apprentices broke ties with him in 307 in the hope of establishing their own holdings in depths. Most went insane or perished, though Jhesirya escaped and later became the Magister of Myth Drannor in 658.
  • Waterdeep was established in 889.
  • Halaster and his apprentices have not been seen in centuries. Whether any of them survives is unknown.
  • The only publicly known (and accessible) entrance to Undermountain is via a 140-feet-deep well located in the basement of The Yawning Portal Inn, where Durnan, the proprietor, will lower anyone who pays a 1 gp fee into Undermountain.
  • The same fee is required to be hoisted back up. For passage to the surface, you must place a gold coin (or something else worth at least that much) into the bucket and yank on the rope. Your fee then is hauled to the surface, where it must be examined and inspected before the cage is lowered to pick you up.
  • Undermountain has connections to Skullport, a subterranean town below Waterdeep where monsters roam the streets and a vibrant trade in illicit goods such as poisons, slaves and kidnap victims. Skullport sometimes is known as the Port of Shadow.
  • Teleportation, divination and scrying don’t work in Undermountain.


Undermountain cschnaars