The South Downs National Park is England's newest national park, designated on 31 March 2010. The park, covering an area of 1,627 square kilometres (628 sq mi) in southern England, stretches for 140 kilometres (87 mi) from Winchester in the west to Eastbourne in the east through the counties of Hampshire, West Sussex and East Sussex. The national park covers the chalk hills of the South Downs and a substantial part of a separate physiographic region, the western Weald, with its heavily wooded sandstone and clay hills and vales. The South Downs Way spans the entire length of the park and is the only National Trail that lies wholly within a national park.

National parks of the United Kingdom are areas of relatively undeveloped and scenic landscape across the country. Despite their name, they are quite different from national parks in many other countries, which are usually owned and managed by governments as protected community resources, and which do not usually include permanent human communities. In the United Kingdom, an area designated as a national park may include substantial settlements and human land uses that are often integral parts of the landscape. Land within national parks remains largely in private ownership. These parks are therefore not "national parks" according to the internationally accepted standard of the IUCN but they are areas of outstanding landscape where planning controls are a little more restrictive than elsewhere.