The Otra river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 is the largest river in the Sørlandet region of Norway

Norway

Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

. It flows from the Setesdalsheiene

Setesdalsheiene

Setesdalsheiene is the collective term for the mountains to the west and east of the Setesdalen valley in Aust-Agder and Vest-Agder counties in Southern Norway. The river Otra flows through the valley between the mountains....

 mountains in Bykle

Bykle

Bykle is a municipality in Aust-Agder county, Norway. It is located in the traditional region of Setesdal. The administrative center is the village of Bykle in the southern part of the municipality. Another village nearby is Nordbygdi...

 municipality in Aust-Agder

Aust-Agder

is a county in Norway, bordering Telemark, Rogaland, and Vest-Agder. In 2002, there were 102,945 inhabitants, which is 2.2% of the total population in Norway. Its area is . The administrative center of the county is in Arendal....

 county in the north, down to the municipality of Kristiansand

Kristiansand

-History:As indicated by archeological findings in the city, the Kristiansand area has been settled at least since 400 AD. A royal farm is known to have been situated on Oddernes as early as 800, and the first church was built around 1040...

 in the south, where it flows into the Skagerrak

Skagerrak

The Skagerrak is a strait running between Norway and the southwest coast of Sweden and the Jutland peninsula of Denmark, connecting the North Sea and the Kattegat sea area, which leads to the Baltic Sea.-Name:...

.

The Otra is 245 kilometres (152.2 mi) long, making it Norway’s eighth longest river. There are many large lakes along the river including: Åraksfjorden

Åraksfjorden

Åraksfjorden is a lake in the municipality of Bygland in Aust-Agder county, Norway. It is part of the Otra drainage basin. The villages of Frøysnes and Skåmedal are located along the western side and on the eastern side are the villages of Sandnes and Åraksbø.The name of the lake was given...

, Byglandsfjorden

Byglandsfjorden

Byglandsfjorden is a lake in the municipalities of Bygland and Evje og Hornnes in Aust-Agder county, Norway. It is part of the river Otra, flowing out of the Åraksfjorden...

, Hartevatnet

Hartevatnet

Hartevatnet or Hartevatn is a lake in the municipality of Bykle in Aust-Agder county, Norway. It is located near the village of Hovden. The lake is a good fishing spot and it contains lots of brown trout....

, and Kilefjorden

Kilefjorden

Kilefjorden is a lake in the municipalities of Evje og Hornnes and Iveland in Aust-Agder county and Vennesla in Vest-Agder county, Norway. The lake is part of the Otra river and was home to the steamship Bjoren from 1866–1896 when it was moved to the Byglandsfjorden.The lake is located about...

. There are 12 hydroelectric

Hydroelectricity

Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...

power plants built along the river, which produce much of the electricity for the southern part of Norway.