National Geographic Society has located the largest underground chamber in the world in a remote cave system in China. The group of spelunkers traveled to that country last year to measure the massive Miao Room, as the chamber is known in caving circles, using a sophisticated laser mapping system. The findings from that expedition were announced this past weekend, with some surprising results.
First discovered back in 1989, the Miao Room has long been considered the second largest chamber in the world, behind the Sarawak Chamber in Malaysia. Measured using standard methods, the massive room is 852 meters (2795 feet) in length, and 191 meters (627 feet) wide. But the new laser mapping system is able to take into account the full size of the room in three dimensions, and it revealed that Miao is larger than Sarawak in terms of total volume. In fact, the Chinese cave occupies about 10.79 million cubic meters (380.7 million cubic feet), which makes it approximately 10% larger than its Malaysian counter part. Sarawak does cover more surface area however, stretching out across an impressive 1.66 million meters.
Expedition co-leader Tim Allen told Nat Geo that finding out that Miao was bigger than Sarawak was akin to "discovering that K2 is larger than Everest!" It has long been believed that Sarawak held the title for the largest underground chamber, but Miao has now stolen its crown.
In order to reach the massive underground room, the explorers had to first descend more than 100 meters (325 feet) beneath the surface, then navigate an underground river. These obstacle were a hinderance to exploring the cave system in the past, which is why it has taken so long to get a more accurate measurement of Miao itself. In order to properly compare it to Sarawak, the same team used their 3D laser mapping system in the Malaysian cave as well.
It is important to point out that these caves are simply the single largest chambers. In terms of the longest overall cave system in the world, Mammoth Cave in the U.S. still holds that title. It stretches for more than 651.8 km (405 miles) with new chambers and passage still being discovered.