Fosen is a traditional district in coastal Trøndelag county, Norway. The district consists of the municipalities Osen, Åfjord, Ørland, Indre Fosen, Orkland, Heim, Hitra, and Frøya. In colloquial speech, Fosen also refers to the Fosen peninsula, (Indre Fosen, Åfjord, and Osen) with the peninsula also having the Southern Sami name Fovsa. In the early 20th century, the region became a site of environmental conflict and activist attention over a wind turbine farm that encroached on reindeer herders of the Sámi people. The Norwegian supreme court ruled in 2021 that the wind farm violated Sámi indigenous rights.

The district is dominated by forested valleys, lakes, coastal cliffs but also shallow areas, and in the interior mountains reaching up to 675 metres (2,215 ft) in elevation. The western coast has many skerries and some islands, such as Stokkøya in Åfjord. There are some good salmon rivers, and sea eagles and other sea birds are very common along the coast, notably on the shallow area near Ørland (Grandefjæra). The west coast has mild winters, and some locations (just west of the mountains) receive on average more than 2,000 millimetres (79 in) of precipitation per year.^{[citation needed]} Part of the Scandinavian coastal conifer forests (Norwegian: Kystgranskog) are located in the valleys of the peninsula, and smaller areas are classified as temperate rainforest with 67 nature reserves. The largest nature reserve is the 5,316 hectares (20.53 sq mi) Øyenskavele, with many nature types including undisturbed forest, some of it classified as rainforest.

Fosen also has a folk high school, Fosen Folkehøgskole. It teaches unusual subjects such as sailing and building traditional Norwegian boats (close to Viking ships), organic agriculture, traditional Norwegian arts and crafts, nature life, etc.

The Fosen conflict [simple] is an ongoing conflict regarding environmentalism. The Supreme Court ruled that two wind turbine parks in Åfjord Municipality, specifically Roan and Storheia, have been built unlawfully. The Supreme Court of Norway ruled in October 2021 that the wind turbine parks violate the indigenous rights of the Sámi people, as the areas form part of official seasonal reindeer herding paths.

The conflict is almost universally referred to as being in the Fosen peninsula as a whole, although only inland central parts of Åfjord contain the involved parks.

The Fosen Conflict has resulted in civil disobedience; in 2023, Greta Thunberg and others were blocking entrances to government ministries in Oslo; the police moved them out of the way. On March 2, 2023, protesters were blocking entrances to government ministries in Oslo; protesters were arrested, brought to the Oslo central arrest and given a fine.

On March 26, 2023, media said that the plans for protests (as of 2 March 2023) included blocking the entrances to the Royal Palace, Oslo; the Norwegian Police Service found out about the plans, and warned that there would be mass arrests; the three main leaders of the protest had doubts that the protests could be kept non-violent if there were mass arrests. instead the protests made a "symbolic blockade", by only blocking the main access road to the palace, so that the attendees of the March 3 government meeting - had to use one of the back entrances.

On 12 October 2023, Sami activists, Natur og Ungdom, Greta Thunberg and others were protesting in Oslo. By 13 October, protesters had set up 3 tents (Lavvo) on the grounds of the royal palace in Oslo.