The cave is the location the Dragonborn will exit 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 or frostbite spiders residing in it. It is also possible to find a cave bear fighting a troll within the cave when first entered. Also, the back wall (which is utilized to enter the cave at the end of Blindsighted quest) 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.
There is a treasure chest that can be found in this area with some potions scattered about it.
- South-west of Winterhold
- Alternitavely, exit Windhelm and head west, following the river until you reach its end which forms a lake.