Þórsmörk valley was named after the Norse god Thor (Þór). Its situated  in the south, between the glaciers Tindafjallajökull and Eyjafjallajökull.

Þórsmörk is famous for having a great variety of natural features. It has been protected since 1921, in the care of the Forestry Service. In the protected valley there is green vegetation of moss, fern and birch wood.

The river Krossá winds between the mountains, a very cold river coming down from the glaciers.