Breiðafjörður is a large shallow bay located in Western Iceland, with an exceptional combination of natural features and cultural and historical heritage. It is approximately 50 km wide and 125 km long, encircled by mountains, including the volcano Snæfellsjökull on the Snæfellsnes peninsula on the south side, and the Western Fjords peninsula to the north. The coast is a fairly narrow strip interspersed with farms and small urban areas. The spectacular land- and seascape consists of shallow seas, small fjords and bays and the inner part of extensive intertidal areas dotted with about 3,000 islands, islets and skerries. The area contains about half of Iceland's intertidal area and over one-third of its coastline. Tides of six metres, unique for Iceland, contribute to the diverse land- and seascapes.
The area has diverse flora and fauna with substantial proportions of the Icelandic population of a number of bird and mammal species, and an intertidal zone high in biodiversity and productivity with extensive algal "forests" and other important habitats for invertebrates and fish, essential in the food chain. The area supports 230 recorded species of vascular plants and around 50 regular breeding bird species. It is the main habitat for the white tailed eagle in Iceland and also important for eider duck. The two Icelandic seal species, the common seal Phoca vitulina and grey seal Halichoerus grypus, have their main haul-outs on habitats in the islands and skerries.