This extensive estuarine area at the mouth of Norway’s largest river, River Glomma, is characterized by shallow areas of brackish water with numerous small islands and skerries surrounded by sediments deposited by the River. The Site also includes meadows, grassland, and forest areas. It is an important area for waterbirds which nest, stage, moult and winter there, including swans and large numbers of ducks in autumn. The Eurasian curlew (Numenius arquata), whooper swan (Cygnus cygnus) and northern pintail (Anas acuta) stage at the Site. The rare tentacled lagoon worm (Alkmaria romijni) has been recorded here, uniquely in Norway. The area is used by local people for birdwatching but also for boating, rod fishing and other recreational activities. A number of extensive scientific studies have been carried out to inform the establishment of the nature reserve which covers the area of the Site. Regulations prevent construction, hunting, drainage and access to resting areas during sensitive periods. The cessation of hay-cutting, grazing and tree-felling has led more nearby areas and islands within the estuary to become overgrown, with the result that some species of plants and birds have become rarer or even disappeared. Measures to reverse this trend have been implemented.