1. The Phong Nha Cave
This cave, from which the name to the whole system and the park is derived, is famous for its rock formations which have been given names such as the "Lion", the "Fairy Caves", the "Royal Court", and the "Buddha". This cave is 7729 m long, contains 14 grottos, with a 13,969 m-long underground river. The scientists have surveyed 44.5 km of grottos in this cave so far, but tourists can only penetrate to a distance of 1500m
Phong Nha Cave, like most of the caves in this area, has been continuously shaped by the Chay River. As one gets farther into the cave, the more illusory the stalactites and stalagmites look as they glitter when bright light is shone on them. The Son River flows into the mouth of the cave and keeps flowing underground, where it is referred to as the Nam Aki River, then this river emerges at a site 20 km to the south near Pu Pha Dam Mountain. The main Phong Nha cave includes 14 chambers, connected by an underwater river that runs for 1.5 km. Secondary corridors branch off in all directions. The Outer Cave and some of the Inner Caves have roofs that tower between 25 and 40 meters above the
water level. From the 14th chamber there may be other corridors leading to similarly large chambers, but this area proves more dangerous for explorers because of the ongoing erosion of the limestone of the cavern. The Shallow Cave is located 800 meters from the cave mouth, where there is a spectacular landscape of sand and rock. Stalactites and stalagmites jut out like strange trees, exciting visitor's imaginations.
2. Vom Cave Systems
3.Tien Son Cave
Tiên Sơn cave is located in Phong Nha-Ke Bang National Park. The cave was discovered by a local inhabitant by accident in 1935. It is located in Sơn Trach Commune in Bố Trạch. The entry mouth of Tiên Sơn is 1 km from Phong Nha cave, at an altitude of 200 m. This cave is 980 m in length. A 10 m deep hole is situated 400 m from the entry mouth, then a 500 m long underground cave, dangerous for tourists and open to professional expeditionists only. Like Phong Nha cave, this cave features spectacular stalactites and stalagmites shaped like several fairy-tales. Stalactite and stalagmite columns and walls here create strange sounds like that of gong and drum if they are knocked with the hand. According to British cave scientists, Tiên Sơn cave was created tens of million years ago when a water current holed this limestone mount in Kẻ Bàng. Following a series of landforms and movement of rocks, this mass was levered or lowered, blocking the current and creating what is now Tiên Sơn cave while the underground river redirected its current to Phong Nha cave. Although Phong Nha and Tiên Sơn caves are located next to each other, there are no linking grottos between them.
4. Thien Cung Cave
Thiên Đường "Paradise" Cave is a newly found cave in this area. Prior to the discovery of Sơn Đoòng cave, it was regarded as the largest and longest cave in Phong Nha-Kẻ Bàng. Some of the most beautiful and spectacular stalactites and stalagmites in the park are found within Thiên Đường. The cave was discovered by a local man in 2005. The first 5 km of this cave was explored by explorers from the British Cave Research Association in 2005; later they in 2010 the whole 31 km was explored and announced by the association.
At 31 km long, Thiên Đường cave is longer than Phong Nha cave, previously considered the longest cave in this national park. The height can reach to 100 m and 150 wide. The limestone formation is also more spectacular than that of Phong Nha Cave. The British cave explorers was impressed by the beauty of the rock formation inside the cave, they named it "Paradise Cave" (Thiên Đường in Vietnamese). Access road and tourist facilities was built by Truong Thinh Group, it was opened up to tourists on 3 September 2010 with a 1.1 km path to see the formations.
5. Son Doong Cave
Sơn Đoòng Cave (in Vietnamese: Hang Sơn Đoòng, meaning Mountain River Cave) is a relatively recently discovered cave in the national park. Found by a local man and explored and publicly announced by the British cave scientists of the British Cave Research Association, it is regarded as the largest cave in the world. The biggest chamber of Sơn Đoòng is over five kilometers in length, 200 meters high and 150 meters wide. With these tremendous dimensions, Sơn Đoòng overtakes Deer Cave of Malaysia to take the title of world's largest cave. Because the fast flowing underground river in the cave deterred the explorers from going farther, they are only able to estimate the length of the cave using a flashlight. The cave had been discovered by a native man in 1991, but he could not remember the way to the cave until January 2008. From late March until 14 April 2009, the local man helped explorers to traverse the 10 kilometer forest pass to access the cave mouth.
The cave was found by a man named Hồ-Khanh in 1991. The local jungle men were afraid of the cave for the whistling sound it makes from the underground river. However, not until 2009 was it made known to the public when a group of British scientists from the British Cave Research Association, led by Howard and Deb Limbert, conducted a survey in Phong Nha-Kẻ Bàng from 10-14 April 2009. Their progress was stopped by a large calcite wall
According to the Limberts, this cave is five times larger than the Phong Nha cave, previously considered the biggest cave in Vietnam. The biggest chamber of Sơn Đoòng is over five kilometers in length, 200 meters high and 150 meters wide. With these dimensions, Sơn Đoòng overtook Deer Cave in Malaysia to take the title of the world's largest cave.