 It was gazetted in 1972 as Thirlmere Lakes State Park, before being subsequently reclassified as a national park.The national park is one of the eight protected areas that, in 2000, was inscribed to form part of the UNESCO World Heritagelisted Greater Blue Mountains Area.The Thirlmere Lakes National Park is the most southeasterly and the smallest of the eight protected areas within the World Heritage Site.