Hang Sơn Đoòng, located near the Vietnam – Laos border, is the largest cave in the world. It is easily one of the wonders of the natural world but, as incredible as it may seem, nobody had set foot in it until 2009. It was discovered by pure chance in 1990 as a local resident, Ho Khanh, was hunting in the jungle. At that time he didn’t enter the cave, but felt the wind coming out of it and could hear the sound of a river. Unfortunately, when he returned, he was unable to locate the entrance, as the surrounding fauna keeps it well hidden. It took him almost 19 years, but finally in 2009 he managed to lead a team of explorers back to the opening and what they discovered was like nothing before seen. The cave spans for more than 9 kilometers and its height ranges between 200 and 500 meters. It was dug between 2 and 5 million years ago by the river’s water, eroding the limestone underneath the mountain. The river is also what gives the cave its name, as it roughly translates to “cave of the mountain river”. The total volume at the time of its discovery was estimated to be 38.5 million cu meter, making it by far the largest known cave in the world. Within it there are two entire jungles and it has its own climate system, which on occasion can even produce clouds. Thanks to the river there are swimming pools, surrounded by total darkness, but amazingly full of life.
Scientists discovered new species of fish, spiders, scorpions, and shrimp, all of them completely white and eyeless, a consequence of a life, deprived of all sources of light. They also uncovered fossils, some of which date back 400 million years, but as of yet there haven’t found any signs of human activity. Nevertheless, the cave is often frequented by monkeys, who have no problem climbing down the 200 meter vertical walls to visit the jungle and collect snails.
In early 2019 the cave got even bigger. The same divers that aided the rescue operation of the trapped football team in 2018 in Thailand aided in the exploration of the underwater tunnels within the cave. They discovered a passage, connecting Sơn Đoòng with another nearby cave, called Hang Thung, adding another 1.6 cu meters to its volume.