Has a Dales rescue team discovered the biggest cave in the world?

Cavers from Craven have become the first people to set eyes on what could turn out to be the world’s largest cave.

A Vietnamese jungle worker, who found the opening to the cave 18 years ago while out hunting, guided the group through leech and snake-infested jungle for six hours to the mouth of the cave system – so large it has its own cloud inside.

Hang Son Doong, Mountain River Cave, is huge. Set in Vietnam’s Phong Nha-Ke Bang National Park, it is estimated to be 200 metres high – nearly 50 metres higher than Blackpool Tower – and up to 150 metres wide.

Until a couple of weeks ago, it had not been seen before.

“We were the first. The guide, Ho Khanh, who we think is aged about 49, had come across it while out hunting food for his family,” said Ian Watson, of West Marton, a member of the six-strong Craven contingent.

All belong to either the Clapham-based Cave Rescue Organisation or the Grassington-based Upper Wharfedale Fell Rescue Association.

“We met him in 2007 and asked if there were any caves where you could hear the wind or water. He said he had seen one once, many years ago, and would look for it,” said Ian.

“He found it the following year, in 2008, and he led the group to seek it out again when we went over in April.”

The group which entered the cave also included representatives of the Hanoi University of Science and what they saw was beyond belief.

The explorers had to battle through intense heat as they made their way down and then, 200 feet down, they were confronted by a raging river.

“It came second to nothing I have seen before, not even the huge cave formations in Borneo. I’ve been all over the world caving and never seen anything like that. It was unbelievable and so huge,” said Ian.

“You’d look at one of the photographs we took and it was incredible to see these small dots on it – the people who were part of our group.”

He said there was no evidence of anyone ever being inside before – no traces of animal bones or other cave dwellers. The echoes and noise from the waterfalls were amazing.

The leading group, consisting of Howard and Deborah Limbert and Martin Colledge, from Ingleton, Martin Holroyd, from Newby, Gareth Sewell, from Utley and Ian, had trekked through jungle for six hours on the day and fought off leech attacks – some bear the scars to this day – foot-long centipedes, poisonous snakes and spiders.

Some of the snakes were so dangerous even the Vietnamese wouldn’t go near.

The group even came across an unexploded bomb half-buried in the sand, a relic from the Vietnam war back in the 1960s.

The trek was not without mishap, much to the expense of Deborah, who slipped and cut her finger to the bone on a sharp piece of limestone. The group had to put eight stitches into her near-severed digit. The danger of potential infection stopped her from going inside the cave.

Several of the group had to stop to remove leeches – one from one man’s groin after he had not noticed it crawling up his leg. Others developed rashes which may have come from the vegetation and then there was painful trench rash, which affected the feet and involved most of the skin coming off.

Another group member was nursing a bruised and cut face after falling out of his hammock.

Getting to the cave was difficult, but the reward was unsurpassed.

“We walked through a different cave system first before we came to the big one. The size of it all was just mind-blowing,” said Ian.

“You could not grasp the distances and, on the photographs we took, we had to circle people who were dots in the distance to be able to make them out.

“Because of its size, it had cloud and that hampered us taking photographs. But we were greatly helped by Hope Technology in Barnoldswick who loaned us a lot of lighting equipment. Without that we wouldn’t have been able to do what we did.”

There were vast pools of water which some of the cavers dived through to see if there were hidden inlets. In other places they squeezed through gaps to see what was beyond.

All the time photographs were taken to catalogue the expedition.

Laser measuring equipment helped them assess the size of the main chamber they explored and the group is now analysing the data.

For Ian, 52, and a member of the Cave Rescue Organisation since 1972, it was his fourth caving trip to Vietnam.

The Clapham and Upper Wharfedale rescue groups have been going every alternate year since 1990, mainly to help a university out there try to find water courses for the region.

They also helped set up an eight-kilometre show cave – Phong Nha (The Wind’s Fang) – in 1994 which now has many thousands of visitors each year and provides half the income for the region.

The Vietnamese are no longer allowed to hunt in the jungle and opening show caves or developing organised expeditions would provide useful income.

Such excursions would have to be managed carefully so people did not climb over the majestic calcium formations created over millions of years, or damage the natural landscape through commercialisation.

However, for the latest discovery there will need to be more excursions to establish just what is actually in that cave system.

“We didn’t have time to go further than five kilometres into the system. That was the size of the main chamber, but we don’t know what is beyond, purely because we ran out of time. It took 16 hours to go from one end to the other,” said Ian.

“At the end we came up against a 40-metre wall and didn’t have the time or the equipment to explore it. Hopefully we will get to do that next year.”

Rumours have been circulating since the find of TV documentary makers becoming involved, but that is speculation at the moment, although it is not beyond the realms of possibility.

Although the group is still examining data and measuring the readings they took, initial feelings are that Hang Son Doong is at least twice the size of the current record holder, Deer Cave, in Sarawak, Malaysia, which is a mere 100 yards high and 90 yards wide.