Lowlands by Héradsflói bay, 40 km north of the town of Egilsstadir, including Héradssandur, Hjaltastadathinghá and the northern part of Hróarstunga. There are riparian marshes with streams, lakes and freshwater pools, and extensive mires dominated by sedges (Carex, Eriophorum).
The area supports a rich variety of breeding waterbirds.
Pressure/threats to key biodiversity
Hunting and shooting pose a threat: Stercorarius parasiticus and S. skua are shot illegally in the area. The area is on the list of sites of conservation interest in the Nature Conservation Register. The site is an enlarged and re-named version of the IBA `Héradssandur-Hjaltastadathinghá', formerly IS050 in the previous international IBA inventory (Grimmett and Jones 1989).