Sơn Động - The World Biggest Cave

Son Dong Cave

Son Dong had somehow escaped detection during previous British caving expeditions to the region, which is rich in limestone grottos.

"The terrain in that area of Vietnam is very difficult," said expedition team member Spillane.

"The cave is very far out of the way. It's totally covered in jungle, and you can't see anything on Google Earth," he added, referring to the free 3-D globe software.

"You've got to be very close to the cave to find it," Spillane said. "Certainly, on previous expeditions, people have passed within a few hundred meters of the entrance without finding it."

The team was told that local people had known of the cave but were too scared to delve inside.

Son Dong Cave

"It has a very loud draft and you can hear the river from the cave entrance, so it is very noisy and intimidating," Spillane said.

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