Southwest National Park is an Australian national park located in the south-west of Tasmania, bounded by the Franklin-Gordon Wild Rivers National Park to the north and the Hartz Mountains National Park to the east. It is a part of a chain of national parks and state reserves that make up the Tasmanian Wilderness World Heritage Area. Covering an area of 6,183 km², it is Tasmania's largest national park.
The park is well known for its pristine wilderness, remoteness and unpredictable severe weather. The area is largely unaffected by humans. Although evidence shows Tasmanian Aborigines have visited the area for at least 25,000 years, and European settlers have made occasional forays into the park area since the 19th century, there has been very little permanent habitation and only minimal impact on the natural environment. Within the area there is only one road, to the hydroelectricity township of Strathgordon. The southern and western reaches of the park are far removed from any vehicular access. The only access is by foot, boat, or light aircraft.