The cavern itself is reached by traversing two levels of Alftand, a Dwemer ruin. The Dwemer theme continues within the cavern, featuring what appears to be a small city that has long since been claimed by Falmer. The northernmost point of the cavern features a Dwemer observatory and a lift to the surface for easy access. It is the only place where Crimson Nirnroot can be found, which was of great interest to the great botanical Alchemist, Sinderion. The cavern also houses many geode veins, which can be mined for soul gems using a pickaxe, as well as an assortment of other ore veins scattered around.
Blackreach can be accessed by descending either Alftand, Mzinchaleft, or Raldbthar. In order to access the entrances to Blackreach, the Attunement Sphere is needed to reveal the stairs leading to each entrance (obtained from Septimus Signus during the Elder Knowledge quest).
There are many auxiliary zones in Blackreach, including:
- Debate Hall — A small Dwemer ruin within Blackreach containing Falmer and Falmer Servants.
- Derelict Pumphouse — A small Dwemer ruin located in Blackreach
- Farm Overseer’s House — A small empty dwemmer house in Blackreach North-West of the Tower of Mzark.
- Hall of Rumination — A small Dwemer ruin located within Blackreach containing Falmer
- Pumping Station
- Raldbthar Deep Market — A Dwemer ruin located on the mountains slightly southwest of Windhelm, between Lake Yorgrim and the White River.
- Reeking Tower
- Tower of Mzark — An abandoned dwemer tower located in Blackreach.
- Silent City Catacombs
- Silent Ruin — A small abandoned dwemmer ruin found in Blackreach, north of the Pumping Station.
- War Quarters — A small building in Blackreach.
- Sinderion’s Field Laboratory — Sinderion’s alchemical foothold in Blackreach.