Undermountain

The Undermountain is the largest, deepest dungeon in the world. The surface entrance is in The Yawning Portal in Drain.

The dungeon was made by an ancient powerful wizard named Halaster, built upon the ruins of the Melairkyn clan of dwarves, which itself was built upon the ruins of Illefarn. It is known for being very dangerous but potentially holding great treasures.

Level 1: The Dungeon Level

Bandits try to rob unwitting adventurers, monsters such as gricks and manticores attack them, and goblins from the Xanathar Guild try to stop them from proceeding lower.

Level 2: The Arcane Chambers

In the second level of the dungeon, the Rustbone tribe of goblins have set up a bazaar for passing adventurers, feeling the pressure from both the Xanathar Guild and Zhentarim who have a presence on the level.

Level 3: Stromkuhldur

Also known as the Sargauth Level, the Legion of Azrok fends off against the invading House Auvryndar.

Skullport

Main article: Skullport