The Song Doong cave is about 4.5km long (2.8 miles), but the explorers from the British Cave Research Association expedition believe that it could be much longer due to the fact that when they studied the cave in Phong Nha-Ke Bang National Park they were blocked by seasonal floodwaters. According to Adam Spillane, one of the expedition's members, for several miles the cave becomes more than 140 by 140 meters (460 by 460 feet).
The entrance to the Son Doong was discovered a few years ago by a local farmer. He led a team of explorers from UK and Vietnam to the cave in April. Back then the researchers managed to discover an underground river that flows through the first 2.5km of the cave and huge stalagmites that were over 70m (230 feet) high.
The size of the cavern was analyzed using extremely accurate laser-based measuring tools. Andy Eavis, president of the International Union of Speleology, confirmed that Son Doong is indeed larger than the Deer Cave. It is worth mentioning that previous expeditions did not manage to come across the cave, mainly because of the difficult terrain in the region, reports National Geographic. Researchers say that Son Doong is located deep in the jungle and there is almost no chance to see it on Google Earth. Explorers mentioned that local people were aware of the cave, but were scared to investigate it, because of the noise that was produced by the loud breeze and the river that runs from the cave entrance. You can read about other interesting discoveries here at www.InfoNIAC.com - check the links at the nottom of the story.
Researchers also managed to spot monkeys that went visited the cave through its top to eat snails. The team looks forward to come back to the cave with a biologist who will examine its subterranean wild life. Explorers believe that there are caves larger than the Son Doong. They think that extremely large caves can be spotted in the heart of the Amazon rainforest.