These are actually the same river with different names for different parts. Its sources are up in the mountains Steinadalsheidi, where it has its third name, Thorarinsdalsa. Its is rather a short river, which system also reaches towards north, wherefrom a few brooks discharge into it. The lowest part is called Fellsa and it discharges into the bay Kollafjordur.
Its surroundings are very beautiful, the vegetation climbs up to the highest peaks around it and there are many good fishing spots to chose from. The sea char is not very big, but interesting
The distance from the capital is about 243 km by the Whale Bay tunnel and 30 km from Holmavik.