River Þingmannaá is a small and beautiful river that comes down from Þingmannaheiði and runs through Þingmannadalur. A considerable number of sea trout have migrated into the river in recent years, and it is often possible to get good catches. Usually, the sea trout come into the river in the beginning of September, but sometimes later. However, this rarely happens except in a good rainy year which is needed to allow the sea trout to migrate. In recent years, sea trout have been making their home in several fishing rivers nationally and this is the case with Þingmannaá. The area has a very beautiful landscape, including waterfalls that have appeared in Icelandic films.