A local farmer had found the mouth of Son Doong cave several years ago in the dense jungles of Vietnam
's Phong Nha-Ke Bang National Park. He led the British expedition team to the cavern in April. The team was told that local people had known of the cave for some time but were too scared to delve inside.
"It has a very loud draft and you can hear the river from the cave entrance, so it is very noisy and intimidating," said caver Adam Spillane, a member of the British Cave Research Association expedition.
Andy Eavis, of the International Union of Speleology, added that there are almost certainly bigger cave passages awaiting discovery around the world.
"That's the fantastic thing about caving," he said.
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Photograph by BARM/Fame Pictures