Find the cave-in.
  • 1 of 4: Talk to Gudrek the Miner (north of entry area), and he'll lead you to the danger zone (if you have Jarl Sven's quest on you to find out why Thjorad production has stopped).
  • 2 of 4: Just walk to the center of the area, and you'll trigger the cave-in.
  • 3 of 4: From where you fall down into the water, you'll have to make your way north and around to get back to Gudrek to report success. (When you reach a boarded-over place, just bash the boards.)
  • 4 of 4: Note that the route from the cave-in back to Gudrek is full of Troglodytes and is a very tough fight for most parties at this point in the game. Don't trigger the cave-in unless you're at full strength and have at least one person who can cast Town Portal in an emergency.