Ånnsjön is a large, nutrient-poor freshwater lake surrounded by extensive mires. The Site includes marshland, a sandy ridge, eroded peat steps, and spectacular waterfalls. Rare inland deltas located at the western and north-western shores of the lake are valuable conservation and educational sites. The mires around the lake are good examples of maritime-influenced mire types. There is a mixture of bogs and fens with a diverse flora. Ånnsjön is very important for migratory and breeding wetland birds such as nationally vulnerable northern pintail Anas acuta, common reed bunting Emberiza schoeniclus and ruff Philomachus pugnax. The Site includes two bird sanctuaries where public access is seasonally restricted. On the steep slope near the lake, in the peat of Klockamyren, there are two 4,600- and 6,100-year-old layers of pine trunks which indicate that the area was then forested. The Site provides livestock fodder for reindeer husbandry by the local Saami population. It also has some value for flood control and is used for hunting, fishing and cloudberry picking. Ånnsjön is a popular birdwatching location, especially in spring and summer. Visitor facilities include footpaths, board walks and birdwatching hides and towers.