Aust-Agder

County of southern Norway, bordering the Skagerrak arm of the North Sea; area 9,212 sq km/ 3,557 sq mi; population (1995 est) 100,200. The rivers Otra and Nidelv run through the Setesdal valley. Nickel and iron ore are mined in the area. Horticulture and forestry are the main sources of income. The county town is Arendal.

The River Otra rises in the high mountains in the north of the county and flows south to the coast and into the Skagerrak. Streams and waterfalls mark its upper course, before the river widens out into a succession of narrow lakes in the lower lands.

The Setesdal valley region is rich in folklore and popular with tourists. The narrow inlets of the south coast around Arendal are used for recreational sailing.