Hengill, a tuff mountain or a mountain range, with widespread geothermal heat some of which has been harnessed. Good hiking in summertime and skiing in wintertime, especially in Innstidalur, the westernmost valley of Hengladalir. Highest point 803 m, Skeggi, a rocky point on the northwest side, overlooking a small valley, Marardalur, a fairly large, grassy plain closed in by cliffs and screes on all sides, with a narrow canyon leading out of it to the west. The valley is easily closed off, and bulls were often kept there. They often managed to escape, however, and roamed the moors, e.g. the Bolavellir meadows (see above). The bulls were fierce and a danger to travellers, other dangers including ghosts, as place names such as Draugahlíð (“Ghosts’ hillside”) and Draugatjörn (“Ghosts’ pond”) indicate.