The biggest natural cave in the world is located in Phong Nha-Kẻ Bàng National Park, Bố Trạch District, Quảng Bình Province, Vietnam. It is known as Sơn Đoòng cave (Vietnamese: hang Sơn Đoòng, IPA: [haːϋ˧ ʂƙ̐ņ ƗƔ̤ዢ˩]).
Hang Sơn Đoòng, which is close to the border between Laos and Vietnam, has the world’s largest cross-section of any cave—it is said to be twice as huge as the next greatest passage—as well as an internal, swift-moving underground river. By volume, it’s the world’s biggest known cave corridor.
There are two possible translations for its Vietnamese name, Hang Sơn Đoòng: “cave of the mountain river” or “cave of mountains behind Đoòng [village]”.
It is thought to be between two and five million years old and was developed in soluble limestone, making it a solutional cave.
Find out
When looking for the rich timber known as agarwood in 1991, a local guy named Hồ Khanh discovered the entrance to Hang Sơn Đoòng. Even though he had originally gone to look around further, the sound of rushing water and the fierce wind coming from the entrance turned him off.
He didn’t think much of it, so by the time he came back to his house, he couldn’t remember where the entry was exactly. Later, while two members of the British Cave Research Association (BCRA) were doing nearby explorations, he casually disclosed his discovery to them.
He was ultimately able to rediscover the entrance in 2008 when they requested him to try, and he led an excursion from the BCRA to the opening in 2009.
The cave was surveyed during this excursion, which took place from April 10 to April 14, 2009, and the volume measured was 38,500,000 m3 (1.36×109 cu ft). The team dubbed the 60-meter (200-foot) flowstone-covered wall the Great Wall of Vietnam, as it prevented them from exploring the entire length of the cave.
After successfully navigating the wall during their return in March 2010, the explorers were able to reach the end of the cave tunnel. They calculated that the cave system’s total length was more than 9 kilometers (5.6 miles).
An explanation
Howard Limbert, the head of the BCRA expedition, claims that the main Sơn Đoòng cave route, which is made of Carboniferous/Permian limestone, is the biggest known cave tunnel in the world by volume, measuring 3.84×107 m3 (1.36×109 cu ft). It is 200 meters (660 feet) high, 150 meters (490 feet) broad, and more than five kilometers (3.1 km) long.
Its cross-section is said to be twice as large as the next greatest corridor, which is located in Malaysia’s Deer Cave. The cavern spans around 9 km (5.6 mi) and is divided by two sizable dolines, which are places where the cave’s ceiling has fallen. Trees and other flora flourish in the cave because of the dolines, which let sunlight into certain areas of the cave.
By the middle of 2019, it was discovered that the cave and a neighboring cave known as Hang Thung were connected by an underground river. This results in an increase of almost 1,600,000 m3 (57,000,000 cu ft) in the cave’s potential capacity.
Some of the world’s highest stalagmites, reaching heights of up to 80 meters (260 feet), may be found in this cave. Unusually enormous cave pearls the size of baseballs were discovered behind Vietnam’s Great Wall.
The inside of the cave is so huge that a Boeing 747 could fly through it without contacting either side, or it could contain a whole New York block, including buildings.
The first party of tourists paid US$3,000 per person to have a guided tour of the cave in the beginning of August 2013. Access to the cave requires a permit, which is only issued occasionally between January and August.
The cave is mostly inaccessible after August due to rising river levels brought on by severe rainfall. As of 2017, the only company authorized to visit the cave for tourism purposes is Oxalis Adventure Tours.
Plans for development
There were plans to construct a cable car that would go through the cave. The suggested system would cost between US$112 and $211 million, and it would be 10.5 kilometers (6.5 mi) long.
Environmentalists and locals, however, rejected the proposals because to the potential harm that mass tourists may do to the cave and surrounding ecology. The municipal authorities finally scrapped the idea.
