The Ölfusá is Iceland's most voluminous river by water flow, the outflow of the enormous Þórsa and Hvítá river systems. It runs through the centre of Selfoss, and the old suspension bridge over it — built in 1891 — was the longest bridge in Iceland when it was erected.
The riverbanks are pleasant for a walk. Brown trout run in the Ölfusá, and you will often see salmon fishermen along the banks in season. The old bridge is now a pedestrian crossing only; the new road bridge carries traffic a short distance downstream.