The unique and picturesque waterfalls called Hraunfossar (Lava Falls) or Girdingar cascade from underneath the edge of the lava field Hallmundarhraun and spill into the glacial river Hvita. The pedestrian bridge across the river was originally built in 1891 and renovated exactly a century later. In the beginning, it was used to drive sheep across the river, but nowadays lorries transport the sheep. Just upriver from the bridge is the so-called Barnafoss (The Children's Waterfall), where there was a natural stone arch across the narrows.

According to the legend, a widow with two children lived at the farm Hraunsas in the past. One Christmas she and her domestics went to attend services at the church at Gilsbakki on the other side of the river. They left the two children at home and could not find them upon returning home. Their tracks led down to the stone arch and it was obvious that they had fallen in and drowned. The mother had the arch demolished and donated the farm Nordurreykir to the church at Reykholt in their memory. The Heidarviga Saga (The Saga of the Slaying on the Heath) mentions this natural stone arch.

The Book of Settlements mentions the sorcerer Musa-Bolverkur, who lived at the farm Hraunsas and says, that he was responsible for diverting the course of River Hvita to the north of the hill Hraunsas, its present course.