The Son Doong Cave is the largest cave in the world. It is so big, it even has its own internal ecosystem. The cave is located right outside of the new adventure capital of Vietnam, Phong Nha.
Despite being anywhere from two to five million years old, it was only discovered in 1991 by a local cave explorer in the area.
However, it only became internationally known in 2009, after a group of cavers from the British Cave Research Association conducted a survey there.
At more than 200m high, 150m wide and 5km long, the Hang Son Doong cave in is so big it has its river, jungle, and climate.
Collapsed ceilings have created openings known as dolines, allowing foliage to grow inside the cave. Microscopic organisms thrive in the darkness.
More people have stood on the summit of Mount Everest than have ventured inside this spectacular natural wonder.
In 2013 Hang Son Doong was opened to the public for the first time, with the adventure tour company Oxalis running the exclusive five-day expedition. Limiting the tour to only one operator has protected the cave from mass development. Only ten customers per departure are permitted. Tours run once per week between February to August per year.
The journey to Hang Son Doong is for the physically active as it requires two days of intense jungle trekking and several river crossings. The nights are spent camping inside the cave and the nearby Hang En, now known to be the third-largest cave in the world.
Once inside, hikers abseil, climb, crawl, and swim through underground rivers to arrive at the end of the cave. The four-day tour is becoming one of the most sought after experiences in the world.
Vital Boost for Quang Binh Provence
The discovery of the cave has been a vital boost for Quang Binh province, one of the poorest regions in the country.
It was as well heavily bombed during the Vietnam war and still has unexploded ordnance scattered throughout the fields and jungle.
Many of the locals still today, collect and dismantle these unexploded bombs, selling the metal and dynamite for scrap.
As tourists began arriving, the locals transitioned into tourism, and thankfully the economy has flourished since then.
Stylish home stays have been built to accommodate adventure seekers from all over the world, which has given the town a new life.
The discovery of 57 new caves has also energized the inhabitants of Phong Nha, who have seen their small town turn into one of the adventure capitals of Asia.