Vietnam: Home to the World's Biggest Caves

Explorers on a 2010 expedition have now measured the biggest cave passage in the world in a remote Vietnam jungle. EarthSky spoke with Darryl Granger, a Purdue University geologist and caver who traveled with the 2010 expedition that measured the true size and length of the cave, which is called Hang Son Doong.
He said the cave is large enough in places to accommodate a city block of skyscrapers. Where the cave opens up to the sky, underground jungles teem with life. A river flows through the underground passage, and it even has its own clouds.
Granger said it is difficult to understand the gigantic scale of the cave.

So when you are looking up at the ceiling, it's like looking up at a giant skyscraper, it's so far away. And from one wall to another, it's the size of a city block. So everything in there is enormous.

Granger described the cave to EarthSky as "green," where jungles grow beneath the cave's skylights.

There were birds flying around. There are actually clouds in there -- it's big enough to have clouds. And there are bugs, things that would fall in and then live in that little small jungle.

Howard and Deb Limbert, a husband and wife caving team, discovered the cave in 2009 with the help of a local farmer. They returned in 2010 to explore the cave further, and make more complete measurements. The expedition team surveyed the cave with laser-based measuring devices. They found that in most places, the cave measures 262 by 262 feet, or 80 by 80 meters, and at its most massive, reaches up to 654 feet, or 200 meters high. Granger said:

It's big enough to fly an airplane through.

Those numbers beat out the previous world-record holder, Deer Cave on the island of Borneo. There are longer and deeper caves elsewhere in the world, but in terms of the size of the underground passage itself, Hang Son Doong is now on top.

Vietnam is renowned for its caves, many of which remain largely unexplored. Hang Son Doon is part of a network of 150 caves in a region of Vietnam that is essentially a giant block of porous limestone. Over millions of years, flowing water burrowing through underground faults carved out massive passages. In some places, the weak limestone ceiling collapsed into massive sinkholes, forming spectacular skylights. Hang Son Doong has the biggest cave passage of them all.
This article was written by Lindsay Patterson in association with EarthSky.org