Nelson Lakes National Park is located in the South Island of New Zealand.

It was formed in 1956 and covers some 1,020 km². It is centered at two large lakes, Rotoiti and Rotoroa. The park also includes surrounding valleys (including Travers, Sabine, and D'Urville, upper reaches of the Matakitaki) and mountain ranges (Saint Arnaud Range, Mount Robert). The park is a popular area for camping, tramping and fishing.

The Park is administered by the Department of Conservation who operate a Visitors Centre in Saint Arnaud that provides up to date and reliable information on all aspects of the National Park.

The main access point to Nelson Lakes National Park is at Lake Rotoiti and the village of Saint Arnaud, on Highway 63, about 100 kilometres from Nelson and 90kms from Blenheim, with connections to Murchison, Greymouth and  Westport.  A secondary access point is at Lake Rotoroa, turning off State Highway 6 at Gowanbridge.

Saint Arnaud is a small alpine village is situated at the northern end of Lake Rotoiti near the historic Tophouse settlement.

The western part of the village includes the local Department of Conservation (DOC) Visitor Centre, with interactive displays and comprehensive information about the wildlife and environmental management of the Nelson Lakes National Park.

The Visitor Centre has a team of professional staff who can offer detailed advice and guidance about all aspects of the area. A number of local footpaths, tracks and nature trails, suitable for all abilities, are maintained by the Department.

St Arnaud village caters for a small number of locals and the tramping and skiing tourists, the centre of Saint Arnaud has a village store with postal services, a petrol station, a cafe-restaurant, camping facilities, motels, chalets and specialist accommodation for trampers.

A water taxi service operates from a jetty at the northern end of Lake Rotoiti, near to a DOC campsite at Kerr Bay. There is another campsite at West Bay.

There are no passenger train services from St Arnaud/Nelson Lakes National Park to Nelson, Picton, Blenheim or Christchurch.