Phong Nha-Kẻ Bàng is a national park and UNESCO World Heritage Site in the Bố Trạch and Minh Hóadistricts of central Quảng Bình province in north-central Vietnam, about 500 km south of Hanoi. The park borders the Hin Namno Nature Reserve in Khammouan, Laos to the west and 42 km east of the South China Sea from its borderline point. Phong Nha–Kẻ Bàng National Park is situated in a limestone zone of 2,000 km in Vietnamese territory and borders another limestone zone of 2,000 km of Hin Namno in Laotian territory. The core zone of this national park covers 857.54 kmand a buffer zone of 1,954 km.
The park was created to protect one of the world's two largest karst regions with 300 caves and grottoes and also protects the ecosystem of limestone forest of the Annamite Range region in north central coast of Vietnam.
Phong Nha-Kẻ Bàng is noted for its cave and grotto systems as it is composed of 300 caves and grottos with a total length of about 70 km, of which only 20 have been surveyed by Vietnamese and British scientists; 17 of these are in located in the Phong Nha area and three in the Kẻ Bàng area. After April 2009, total length of caves and grottoes are 126 km. Before the discovery of the Sơn Đoòng Cave, Phong Nha held several world cave records, as it has the longest underground river, as well as the largest caverns and passageways.
The park derives it name from Phong Nha Cave, containing many fascinating rock formations, and Kẻ Bàng forest. The plateau on which the park is situated is probably one of the finest and most distinctive examples of a complex landforms in Southeast Asia. This national park was listed in UNESCO's World Heritage Sites in 2003 for its geological values as defined in its criteria viii. In April 2009, the world's largest cave, was discovered by a team of British cave explorers of British Caving Association