Arundel Park is a 134-hectare (330-acre) biological Site of Special Scientific Interest north of Arundel in West Sussex. This old deer park on the chalk of the South Downs has an ancient artificial lake, Swanbourne Lake. The site is described by Natural England as one of the most important sites in the country for invertebrates. There are fifteen endangered species, including the field cricket Gryllus campestris and the beetle . Another rarity is the mollusc . There is also a diverse breeding bird community. The site is open to the public.