Phong Nha–Ke Bang National Park

Phong Nha–Ke Bang is a big park in Vietnam.

It has steep green hills made of a rock called limestone. Rivers run into the hills and through dark caves. Some caves are giant. Monkeys and lots of other animals live in the forests.

Phong Nha–Ke Bang National Park lies in central Vietnam, close to the border with Laos, in the Annamite Mountains. It protects a karst landscape: steep limestone hills, cliffs, deep sinkholes and rivers that disappear underground into caves. UNESCO calls it one of the most outstanding and intact limestone karst landscapes in the world.

UNESCO made the park a World Heritage Site in 2003. In 2025 the site grew to include Hin Nam No National Park, just across the border in Laos, so the two countries now protect it together. More than 220 kilometers of caves and underground rivers have been explored and mapped, and some of them are among the largest on Earth.

UNESCO describes Phong Nha–Ke Bang as lying at the junction of the Annamite Range and the Central Indochina Limestone Belt. Since the 2025 transboundary extension, the World Heritage property joins Phong Nha–Ke Bang National Park in Viet Nam with Hin Nam No National Park in the Lao People's Democratic Republic: 217,447 ha in all, surrounded by a 295,889 ha buffer zone that covers the karst's watersheds.

The park was first established in 1986 and enhanced in 2001; UNESCO inscribed it in 2003. Its landscape combines dramatic cliffs, deep sinkholes and a vast network of underground rivers, with more than 220 km of documented caves and subterranean waterways. UNESCO calls it among the largest intact humid tropical karst systems on Earth and notes that, on the surface, the diversity of its polygonal karst features had been recorded nowhere else at the time of the extension.

Son Doong is one of the biggest caves in the world.

A huge hole in the roof lets in the sunlight. Trees and ferns grow inside the cave! Clouds can even float near the ceiling.

Son Doong means mountain river cave. A local man, Ho Khanh, found its entrance as a boy but forgot where it was, then found it again; in 2009 British cavers led by Howard and Deb Limbert became the first team to explore inside. National Geographic reported that the cave is more than 4 kilometers long, with a passage up to about 90 meters wide and, in places, more than 180 meters high.

Where the roof has fallen in, sunlight pours down, and a jungle of trees, ferns and vines grows on the cave floor. A botanist found mostly the same plants as in the forest above. Inside, explorers also met woodlice, fish and millipedes that are all white, which is common for animals that live in the dark.

National Geographic (January 2011) describes the first expedition into Hang Son Doong in spring 2009 by British cavers led by Howard and Deb Limbert, helped by Ho Khanh, who had found the entrance as a boy and relocated it only the year before. The 2009 team explored about 4 km before a 60 m calcite wall, the 'Great Wall of Vietnam', stopped them; the 2010 team climbed it. Laser surveys showed a passage more than 4 km long, as wide as about 90 m and in places over 180 m high; from the bottom of one section to the ceiling the cavers measured about 200 m.

Collapsed dolines admit light: beneath the first, a calcite tower over 60 m tall carries ferns and palms, and the skylights are large enough for trees, lianas and wispy clouds. Biologist Anette Becher found white woodlice, fish and millipedes, typical of dark-adapted animals, and botanist Dai Inh Vu found mostly the same plant mix as the forest above. UNESCO notes that some invertebrates and fish in the property are restricted to single cave systems.

The park is covered in thick green forest.

Thousands of kinds of plants grow here. Many kinds of monkeys and apes swing through the trees. Some animals live in only one cave in the whole world.

The limestone hills are covered with forests, from dry forest on high karst to thick, moist forest lower down. UNESCO counts more than 2,700 kinds of plants and 800 kinds of animals with backbones in Phong Nha–Ke Bang alone, and says the real numbers are probably higher.

The park and its partner in Laos are home to 10 or 11 kinds of primates. They include the largest remaining group of southern white-cheeked gibbons and the black langur, a monkey found only in this region. Rare orchids and begonias grow here, and some small animals and fish live in just one cave system and nowhere else.

UNESCO places the property within globally significant ecoregions, including the Northern Annamites Rainforests and the Annamite Range Moist Forests, and attributes its high endemism to the complexity of the limestone landscape, which created many ecological niches and allowed speciation at the landscape level. Endemic species occur above ground (several orchids and begonias) and below ground (invertebrates and fish confined to single cave systems).

At the time of inscription, Phong Nha–Ke Bang recorded over 2,700 vascular plant and 800 vertebrate species, including 237 globally threatened species and 400 species endemic to central Laos and/or Viet Nam; Hin Nam No adds over 1,500 vascular plants and 536 vertebrates, including the giant huntsman spider, the largest spider by leg span. The property holds 10 or 11 primate species, four endemic to the Annamites, including the largest remaining population of southern white-cheeked gibbon and the endemic black langur. UNESCO lists illegal hunting, overharvesting, invasive species, infrastructure, land-use change and tourism pressure among the threats.