A small, short three rod river in the middle of the Southland. It originates in the lake Heidarvatn just north of the village Vík, and flows two kilometers into the glacial river Kerlingadalsa. The Vatnsa, though small, has a haunting beauty and utterly unique surroundings. Having carved its way through a soft bed of rock, it is dotted with caves, tunnels and large rocky mushrooms. All the terrain is thickly vegetated. The river itself is narrow and fast flowing but still slows sufficiently now and then allowing Salmon and Sea Trout breathers.  The Salmon starts running in late July and continues throughout September.

The Sea Trout starts about mid August and continues far into autumn. They tend to drift into the lake while the Salmon stay longer in the river. Both spawn in the river though. This river is prolific, usually producing an annual catch of 100 to 150 and after Salmon have bean released  from man made lagoons to the river the catching has increased up to 800 salmon per season and 150 to 250 Sea Trout.
See fishing Statistic

The distance from the capital is about 200 km and 10 km from Vik.