Exploring inner space in Middle Earth
The first question many would ask of the country's leading cavers is, "Why?" Alastair Paulin reports.
Imagine you're 600 metres underneath Takaka Hill. It's dark, wet and cold. The rubble you are crawling over is coated in slick mud and your feet are getting jammed in cracks.
You have to contort your body to push forward through the narrow passage, pushing headfirst into the unknown, only to find yourself stuck in a tight squeeze between boulders. Somehow you have to turn yourself around to get through the next squeeze backwards. You may find yourself in a vertical rift with no real top or bottom and if you relax your muscles, you'll slip down into a narrow passage that may be too tight to extricate yourself from.
If things go wrong, they can go very wrong. Your caving colleague above you could dislodge loose rock that falls on your head. You could fall and break a bone. A flash flood could sweep through the underground caverns, leaving you nowhere to seek refuge. And it's not as if a helicopter can fly in to find you. Only a small group of people have the technical skills and equipment to rescue you from the previously undiscovered passage.
Bruce Mutton has been dropping down sinkholes to explore the enormous system of caves below Takaka Hill for 28 years. The Nelson structural engineer and Motueka doctor Michael Brewer have seen more of the underground wonderland that water has carved from the Marble Mountain's interior than anyone else. And in the last four years, they, along with teams of colleagues, have discovered more kilometres of new passages than had been discovered since cavers first dropped into Green Link from an opening near Canaan Rd in 1974.
In the first week of March, the pair were part of a team of six cavers who spent five days underground and pushed the charted system of Green Link/Middle Earth out to 31.5km. In the process, they edged 200m closer to the Riwaka Resurgence cave system. If they were to find a passage between the two, it would create a system that stretched more than 50km, making it the second longest in the country. It would be, says Brewer, "one of the most unpleasant through trips known".
And yet they keep returning. Mutton doesn't know how many times he has explored the caves - he was introduced to the cave in 1986 as a 24-year-old, soon after he moved to Nelson for the caving. He only started keeping records in 2000. But over the last several years, he, Brewer and others have been going on two or three day trips every few months.
He can't quite pin down what draws him back but part of it is the thrill of new discoveries and part is enjoying the physical and mental challenge he faces on every trip.
"I like the rock climbing, navigating the obstacles, I like the isolation and I like the water." And since he has taken on the mantle of maintaining the maps of the systems, he enjoys the intellectual puzzle of mastering the arcane software the team uses to collaborate on charting the caves.
Westport caver Neil Silverwood, who was on the five-day trip along with Ruby Bay's Richard Bramley, James Alker from Motueka, Ben Davidson from Nelson and David van der Gulik, says new technology has been a key to why this is now the "golden age of caving".
"The cave is being surveyed using a laser which measures length, inclination and direction as well as the distance to either wall. Using Bluetooth and a rugged palm top computer, the cave can be mapped quickly and very accurately. Being able to see the cave mapped as you go and knowing exactly where you are is incredible and a huge step forward."
Powerful LED lights enable cavers to see into nooks and crannies that were previously too dim, and rotary hammer drills make putting in climbing bolts easier and faster. At the same time, the cavers are aware they are in a fragile, beautiful environment, and there is, says Mutton, a constant tension between the urge to explore and trying to minimise their impact. They try to walk in the same places as previous cavers, and sometimes come across footprints that they know must be from explorers of decades ago.
They also have a unique perspective on how land use above them affects the caves, with much of the sediment in the caves coming from logging operations of half a century ago, he says.
Although the goal of connecting the Green Link/Middle Earth system with the Riwaka Resurgence is suddenly looking possible, the two systems are still 1100m apart. Cavers have known they connect since 1976, when a team led by Van Watson put 4 kilograms of dye in a Green Link stream. The dye turned the source of the Riwaka River bright green, proving a hydrological link between the systems and leading the local council to believe there had been an algae bloom in the river.
But 1100m is a long way when you're jamming yourself through muddy squeezes that may lead nowhere and just because water can seep through doesn't mean there are man-sized passages. "When will it connect?" says Mutton. "Maybe never.
"Personally, I don't really care. I'm just happy to explore and find what we find."
There are plenty of other promising, and closer, passages yet to explore, and who knows what they may discover along the way. The thrill of exploration and of charting previously unknown places will keep drawing them back underground.
As Mutton says: "We've made New Zealand bigger."