VIETNAM – UNDATED: ***EXCLUSIVE*** The British caving team crossing one of the underground rivers inside the Hang Son Doong cave in Ke Bang Massif, Vietnam, April 2009. A British Caving team believe they have discovered the largest sized cave passage in the world. Measuring 200 metres in height and 150 metres in width the new cave, called Hang Son Doong (Mountain River Cave), is 6.5 km long. Assisted by representatives of Hanoi University of Science the team explored the new cave for five days. The team spent six hours trekking through the jungle to reach the cave. Climbing down into a large chamber, they had to negotiate two underground rivers before reaching the main passage of the Hang Son Doong. The team will return to Vietnam later in the year to complete the expedition of the cave and conduct a full survey. (Photo by Joint British-Vietnamese Caving Expedition 2009 / Barcroft Media / Getty Images)
