Called Hang Son Doong (Mountain River Cave) it is believed to be almost twice the size of the current record holder. Son Doong has replaced the Deer cave in Malaysia to become the world’s largest cave.

‘It is a truly amazing sized cave and one of the most significant discoveries by a British caving team,’ said Adam Spillane, a member of the 13-man expedition team.

The cave was originally discovered in 1991 by a Vietnamese Jungle man called Ho Khanh. However Mr Spillane said no-one had entered if before because: ‘it emitted a frightful wind and noise which was due to a large underground river.’

They spent five days exploring the cave in Vietnam’s Phong Nha-Ke Bang National Park through mid-April.