Otra

The Otra is the largest river in Norway's Sørlandet region. It starts in the Setesdalsheiene mountains, near Lake Breidvatnet in Bykle municipality in Agder county, just south of the border with Vinje municipality in Vestfold og Telemark county. The river then flows south through the municipalities of Bykle, Valle, Bygland, Evje og Hornnes, Iveland, Vennesla, and Kristiansand. The river empties into the Skagerrak in the center of Kristiansand on Norway's southern coast.

The Otra is Norway's eighth-longest river, measuring 245 kilometers (152 miles). Åraksfjorden, Byglandsfjorden, Hartevatnet, and Kilefjorden are just a few of the large lakes along the river. Along the river, 12 hydroelectric power plants have been built, producing a large portion of Norway's electricity.

Because the water in the Otra River is not too acidic, salmon thrive there. The calcareous rocks in the catchment area at the northern end of the Setesdal valley provide a buffer capacity for the water against acidification.

Length: 245 km (152 mi)