Viðarfjall
The walk up to Mt. Viðarfjall is rather easy and there is a marked trail. You can start the hike from Litla-Viðarvatn which is a small lake by road 85. From Viðarfjall there is a great view over Þistilfjörður, Langanes and Melrakkaslétta. When you reach the telecommunication mast on the mountain it's ideal to walk on to Geirlaug which is the highest point of Viðarfjall on the north side of the mountain, 369 m over sea.
Beautiful view from Geirlaug on the picture.