believed to be twice that of the next largest passage. It is the largest known cave passage in the world by volume.
What is Son Doong Cave?
According to a paper published by a team of explorers that explored the cave, the number of species found in the cave over a period of three years between 2008 and 2010 was 150, comprising 80% of all mammals living in caves, and more than half
Sơn Đoòng cave is one of the world's largest natural caves. Located near Laos–Vietnam border, Hang Sơn Đoòng has an internal, fast-flowing subterranean river and the largest cross-section of any cave,
worldwide, as of 2009, believed to be twice that of the next largest passage. It is the largest known cave passage in the world by volume.
What is Son Doong Cave?
Most cave systems in the world are formed by the accumulation of rainwater over millions of years, particularly in the form of groundwater coming in from underground springs.
Not all caves form in this way; there are also karst caves formed by precipitation and runoff, in which the water flow was built up over millions of years, ultimately collapsing from the over-abundance of water.
But in rare cases, caving and exploration efforts have exposed new cave formations, which sometimes form by the removal of the overlying rock from the underlying limestone.
In these cases, the formations are found in the soft, more fragile rock below the overlying limestone, which is much more susceptible to erosion.
The director of the exploration team, Rolando Pablos, says, "If the depths of Sơn Đoòng represent a world, this is an undersea continent." The cave has a length of 4.5 km and is 800 m high.
The entrance is 360 m long and the fastest recorded rate of vertical descent is 70 m per minute. Access The cave has several entrances, but only two are usable.
The best known of these is the main entrance and upper access shaft, reached by ascending a narrow and winding 110-metre staircase from a camp at the surface.
The other entrance, 10–15 metres higher, is the main entrance shaft's exit route, most frequently climbed. Climbers ascend a horizontal tunnel 2.5 metres high, through which the limestone walls rise up to 80 metres.
The man behind the discovery
According to an article in National Geographic, the son of a Vietnamese property developer was having drinks in a bar on his home town's secluded southern edge, drinking iced tea and chatting with a local guide when the subject of caving came up.
The owner of the bar, who had family working on a resort in the nearby town of Da Lat, shared an interest in the caves and introduced the two to each other.
A few months later, the owner's son went with a local guide to spend a weekend in the caves, prompting the search for a group to share the expense of another excursion.
In 1999 the owner of a fishing boat in Da Lat, who had family who worked at the nearby Vinpearl resort, expressed an interest in paying to send a group on an exploration trip.
How to visit this incredible place
In 2003 a Vietnamese man, Phạm Văn Trà, was hired by the cave's operator, Stauffer, as a local guide.
The cave, although spectacular, was not very well known. It was believed to be the most visited cave in the world.
Two years later, the agency hired another guide, Duy Tân. Trà didn't want to get mixed up with these two guides and left the area.
They spent much time taking pictures of each other, including some revealing photos of them in a private embrace.
Phạm Văn Trà's brother then released the photos and set the world on fire.
The media began speculating that these two men were husband and wife and got married in the cave.
Son Doong Cave is regarded as the second-largest cave system in the world, the largest being the Mono cave system in Mexico with 9,000 km2 (3,600 sq mi).