Terramok

Terramok is located in Maraudon in Desolace.

The crystal caverns of Terramok lie deep within Maraudon.

Cho'gall says that Terramok was a vault of the Titans, and that Theradras was no longer are you bound to this prison. Theradras refers to the place as her home and even though it was once her prison and she was bound there, she would never leave it.

Therazane claims that her daughter sequestered herself deep within the Crystal Caves of Terramok to grieve for her lost love, Zaetar. She was then killed by fleshlings.

In the RPG
Behind a series of spiked barriers in the center of the mesa stands Terramok, an ancient titan vault. This place is rumored to hold Theradras, former princess of the vile earth elementals and legendary mother of the centaur race. Some even claim that Theradras guards the tomb of her husband, the Keeper of the Grove killed by the first khans.

Speculation and notes

 * Translating the Warcraft: The Roleplaying Game info to World of Warcraft, the "spiked barriers" seem to be the Valley of Spears, "the mesa" seems to be Valley of Spears counted as a part of Maraudon, and Terramok seems to be the underground portion of the area. However, the RPG is non-canon. Still, that seems to be what the initial concept was.
 * Per the "Twisted Evils" quest, Terramok appears to be part of inner Maraudon, but the extent of it is unknown.
 * It appears that elementals can only be permanently killed on their home plane, and Therazane refers to Theradras as dead, so it does seem that she was bound here instead of the Elemental Plane, as she tells Cho'Gall. It is unknown why Theradras was bound to Terramok and not Deepholm.
 * Terramok's name may be derived from, a Latin word meaning earth.