Elevated from nature reserve to National Park in 2001 and inscribed on the list of UNESCO World Heritage Sites in 2003, Phong Nha-Kẻ Bàng National Park covers an area of 85,000 hectares and incorporates Việt Nam's oldest limestone mountain range, with many of its unexplored peaks towering to over 1,000 metres. The Park is known chiefly for its extensive cave complex, in particular the Phong Nha Cave, and boasts many fascinating rock formations, long underground rivers and wide pristine sandbanks. Its tropical rain forest is home to 36 out of the 750 rare plant species listed as endangered in Việt Nam's conservation red book. The site is located some 50 kilometres north west of Đồng Hới, capital of Quảng Bình Province, and may be accessed by car and boat.