The world's largest cave

The world's largest cave has its own climate, jungles, rivers and clouds inside

Sơn Đoòng is the world’s largest cave, located deep in the jungle of Vietnam. The name "Sơn Đoòng" means "mountain river cave".

It was formed 2-5 million years ago by river water eroding away the limestone underneath the mountain.

The cave was found by a local man named Hồ Khanh in 1991, but it was only in 2009 that it become internationally known after a group of British cavers re-discovered it.

They had heard of Hồ Khanh's fabled discovery, and contacted him to request his help finding the cave.
It took several months, but he eventually retraced his way back through the remote jungle to once again locate it.

What they found was astonishing. The cave is more than three miles long, with some chambers large enough to hold an entire city block of New York skyscrapers.

It's so huge, that the cave has its own climate, complete with clouds, and contains an entire rain forest with running rivers.