The cave is the location the player will exit out of at the end of the Thieves Guild quest, Blindsighted. The cave is a simple tunnel, serving only as an exit from the dwarven ruin, Irkngthand. If you enter the cave before completing Blindsighted you may find a couple of Cave Bears residing in it. Also, the back wall (which the player will use to enter the cave at the end of Blindsighted will be inaccessible due to a bunch of rocks filling the tunnel.
There is a note inside the torture chamber of Irkngthand that will explain how the torture victim's friend escaped through the tunnel leading into the cave, but that he doesn't know if he made it or not because there was a cave-in. This could be the in game explanation for the rocks blocking the tunnel if you enter the cave before the quest.
Orcish Boots of Muffling was in a dwarven chest and a few potions are scattered around
- South-west of Winterhold
- Alternitavely, exit Windhelm and head west, following the river until you reach its end which forms a lake.
- Unique Weapon: Nightingale Bow