A British caving team believe they have discovered the world's largest cave passage in the heart of the Vietnamese jungle.
The rocky passage is 150metres long and measures a towering 200metres in height - seven times as high as the vaulted ceiling of York Cathedral.
Called Hang Son Doong (Mountain River Cave) it is believed to be almost twice the size of the current record holder.
'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.
Using a laser measuring device known as the LaserRace 300, which measures height and width, the team are now back in the UK analysing their readings.
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'.
But assisted by representatives of Hanoi University of Science, the joint British-Vietnamese Caving Expedition 2009 spent five days exploring the cave in Phong Nha-Ke Bang National Park in mid-April.
The team spent six hours trekking through the jungle to reached 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.
'The cave is 6.5km long at present but the end of the main passage still continues with a calcite wall of over 45m high halting our progress,' Mr Spillane said.
'More work on the next expedition is required to make a complete exploration of Hang Son Doong and obtain a complete photographic record of the cave.
'It is a great achievement in this day and age to discover and explore such a fantastic cave.'
The rocky passage is 150metres long and measures a towering 200metres in height - seven times as high as the vaulted ceiling of York Cathedral.
Called Hang Son Doong (Mountain River Cave) it is believed to be almost twice the size of the current record holder.
'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.
Using a laser measuring device known as the LaserRace 300, which measures height and width, the team are now back in the UK analysing their readings.
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'.
But assisted by representatives of Hanoi University of Science, the joint British-Vietnamese Caving Expedition 2009 spent five days exploring the cave in Phong Nha-Ke Bang National Park in mid-April.
The team spent six hours trekking through the jungle to reached 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.
'The cave is 6.5km long at present but the end of the main passage still continues with a calcite wall of over 45m high halting our progress,' Mr Spillane said.
'More work on the next expedition is required to make a complete exploration of Hang Son Doong and obtain a complete photographic record of the cave.
'It is a great achievement in this day and age to discover and explore such a fantastic cave.'
