An open fissure in an oval hyaloclastite mount named Lambafell. The fissure is only few metres deep. It is possible to hick along the entire fissure on the summer time. In the walls of the fissure are excellent outcrops of subglacially formed basaltic pillows.
Location: The walk takes about 1 hour. Take road to Höskuldarvöllur and then drive down to Trölladyngja. Park at the parking at Eldborg and walk east of Eldborg to Lambafell.