The Site is composed of a shallow marine bay located around the mouth of the Nordre älv River; it includes about five kilometres of the river, several small sheltered bays and a large number of islands and isles. The riverside includes a multitude of nature and vegetation types, such as meadows, fens, reed-swamp, rush, sedges, deciduous forests and rocky areas. The shallow marine areas include highly productive waters and eelgrass (Zostera marina) beds, an important habitat included in the OSPAR List of Threatened and/or Declining Species and Habitats. This large area offers shelter, nursery areas for flatfish and feeding grounds for waterfowl. Large numbers of waterbirds are supported, especially waders and ducks, and fish production is very high and commercially important. The Site holds important spawning ground, nursery and feeding area for several fish species including the (globally) critically endangered eel Anguilla Anguilla. The beautiful landscape and cultural history make the area extremely attractive for tourism and recreation, especially boating. Potential threats to the ecological character of the Site relate to pollutant discharges, changes in sea currents, landfilling and construction of dikes to increase areas of dry land, and anchoring of buoys and bridges and other construction in the water.