|Appears in||Redguard, ESO|
Bthzark was built by the Rourken clan, who left Morrowind to settle the wastes of Hammerfell after refusing to join the First Council. The complex was built with a distinct architectural style, and its many machines are powered entirely by a system of steam pipes. Bthzark also contained a large mine, which became partially flooded with lava at some point. The complex was left abandoned after the Dwemer's disappearance in 1E 700 and fell into ruins, although one of the entrances was sealed shut and prevented looting. The Dwemer presence on the island left a long-standing influence, inspiring the use of Dwemer pipes in Port Hunding and allowing the island's future inhabitants to study the stars using the Dwemer observatory near Saintsport.
At one point the ruins contained a coveted Dwemer schematic, although a team of sellswords were betrayed from within and killed by traps while they attempted to recover it. In 2E 582, an Altmer scholar named Neramo came to Stros M'Kai to recover the schematics for himself. With the help of the Soulless One and a tamed Dwarven Spider, Neramo was able to use focusing crystals to access the ruins, fight past the traps and guardians, repair the broken machinery, and ultimately reach the schematics.
In 2E 864, Cyrus entered the ruins to recover a Dwemer gear in order to repair the island's observatory. Using a book on Dwemer runes, he was able to unseal the entrance, and managed to manipulate the ancient machinery to continue deeper into the mines. Among the obstacles that faced him were a complex mechanical scarab puzzle, Dwemer constructs, and a colossal Dwarven Centurion. It was from the wreckage of this Centurion that he was able to salvage a spare gear.
- To unseal the entrance, Cyrus said the phrase, "Shahbth ih awerk. Stuh ndah bthahhrk. Awerd sheh ahhmmzrteh."