Coldharbour is the plane of Oblivion that is associated with Molag Bal. It resembles that of Nirn, but the ground is nothing more than sludge; the sky constantly burns, and yet the air is beyond freezing. Even an alternative Imperial Palace, as described in The Doors of Oblivion, is known to be there, but dripping with blood and laden with corpses. Coldharbour is known as one of the most inhospitable realms of Oblivion.
Since Molag Bal's sphere is domination and the enslavement of mortals, and because he is known as the God of Schemes, it is no wonder that any mortal entering the realm is captured, enslaved and turned into one of Molag Bal's Soul Shriven, soulless slaves laboring for eternity under Molag Bal's command.
This realm is known for its vast slave pens and laborers, bleak, dead rocky chasms and twisted, abandoned ruins, some ripped straight out of Nirn such as the Argonian village of Haj Uxith.
Daedra are known to wander the realm and to be among the servants to Molag Bal. Some Daedra in Coldharbour include Harvesters, Dremora, Scamps, Soul Shriven and atronachs, though there are a vast number more.
Some believe Coldharbour to be a premonition of Nirn's future.
It was revealed in Dawnguard through conversation with Serana and Harkon that those females who were turned into Vampire Lords during a ritual with Molag Bal were known as the Daughters of Coldharbour.
In The Elder Scrolls Online, Molag Bal tries to merge Nirn with Coldharbour using massive inter-planar machines known as Dark Anchors. With the barrier between realms weakened and the Dragonfires darkened, Molag Bal is able to launch a full-scale invasion of Tamriel. It is up to the Soulless One, one of Molag Bal's former slaves, to topple the God of Schemes and the Planemeld in order to save Nirn.
- The Elder Scrolls IV: Oblivion (Mentioned only)
- The Elder Scrolls V: Skyrim (Mentioned only)
- The Elder Scrolls V: Dawnguard (Mentioned only)
- The Elder Scrolls Online