Ástjörn and Ásfjall were designated as a country park in 1996. The country park surrounds the Ástjörn Nature Reserve, which includes the pond and its immediate surroundings and has been protected since 1978. Ásfjall offers extensive views and is of particular interest to those interested in the geology and history of the capital region. Remains associated with the military presence in Iceland during the Second World War can also be found on the mountain.
Ástjörn is a distinctive natural feature with no comparable habitat in the immediate vicinity of the largely continuous urban area of the capital region. The pond and its surroundings support a rich diversity of plant and animal life. It was once home to the only known breeding site of the horned grebe in southwest Iceland. The species has declined considerably since the first half of the 20th century and is protected and included on Iceland’s Red List.
The pond also supports a rich invertebrate community, although it has been relatively little studied.
The country park covers 56.9 hectares.