On the South Island of New Zealand, JANE LANGILLE and her family enjoy blackwater rafting in a surreal underground landscape, drifting in pitch black darkness under thousands of glow-worms.

Our half-day adventure started early in the morning in a van, careening around the curvy road. There are no straight roads anywhere in New Zealand. Brendan and Rus, our tour guides for the day, were planning the day’s excursions and had picked us up at our motel in Westport. Their banter was difficult to tune in as we had only been in New Zealand for five days and were still adjusting to the Kiwi accent. They thought we sounded like Americans, until we suggested that they sounded like Australians. From that moment on, Brendan and Rus branded our family of four “Team Canada.”

The blackwater rafting adventure in Paparoa National Park was one of the many planned highlights of our four-week road trip exploring New Zealand. (The sport gets its name from the pitch-black caves that rafters drift through.) Paparoa National Park covers 30,000 hectares of very wild land in the northwest coastal area of the South Island. It was created as a reserve in 1987 with carefully chosen boundaries to encompass a diverse range of ecosystems from karst limestone cave formations, rainforests, granite summits and the famous scenic attraction of coastal cliffs and blowholes known as Pancake Rocks.

The tour guides brought my husband and me, along with our children, aged 13 and 11, to Norwest Adventures’ underworld rafting base in Charleston, which consisted of a shack of adventure gear at the back of a roadside diner. Charleston is a tiny village, about 25 kilometres south of Westport, left over from the gold rush of the 1800s — blink while driving through and you will miss it altogether. At the peak of the gold fever around 1870, Charleston’s population swelled to 40,000. Today, the population is recorded by one local mining historian as “130 in the summer and 80 plus one old grump in the winter.” We collected our required gear — full wetsuits, helmets with lights and life jackets — and piled into vans with seven other tourists. Access to Paparoa National Park is limited, so the vans drove us down a small hilly road to a miniature train station in the jungle. Somewhat reminiscent of the train in Jurassic Park, the Nile River Rainforest Train chugged on narrow tracks through the jungle while Marilyn, the train driver, gave a little spiel about the park. The topography of limestone cliffs and rock formations reminded us of the Niagara Escarpment, except we were passing large fern trees and lush jungle foliage alive with the sound of exotic birdcalls. Brendan and Rus hung out the sides of the moving train to hack away the overgrowth of vegetation with garden loppers to keep the path clear.

We arrived at a clearing in the bush and disembarked. The trees were buzzing with the sound of cicadas. We found our change area, which consisted of a large wooden pallet on the ground in the clearing. Brendan explained that peeing in the tour company’s wetsuits was “not an option.” If anyone felt that three hours would be too long, they were free to use the “facilities,” he told us while gesturing into the jungle behind some trees. I strode up to find some privacy but had to watch my step, as there were huge plops of cow scat on the jungle floor. Cows in the jungle? Apparently, local farmers allow their cattle to graze in the clearing.

We divided into two groups, Team Canada with Brendan, and the seven others — a couple of local Kiwis and some Americans — collectively labelled the Black Sheep, with Rus. We collected our inner tubes and waded through the refreshing water, crossing the Nile River to reach the steps leading to the cave entrance. The Black Sheep used the footbridge instead, which had been built in 1876 during the gold rush, one of the earliest suspension bridges built in New Zealand. After climbing a hill of about 80 wooden steps, and feeling quite warm in the wetsuits on this hot summer day in February, we arrived at the mouth of the cave known as the Triclops Entrance. This large hole in the side of the hill is large enough to walk into upright. The cave system was relatively unmodified; save for a few rope trails on the floor that a group of Boy Scouts had installed about 20 years ago.

The Nile River cave was full of fresh air and never felt constricting. As the river originates in the cave system, the water level must be sufficiently low for blackwater rafting tours to operate. Brendan, with his vast knowledge of the geology of this underground karst landscape, explained the differences between stalagmites and stalactites. We saw unbelievably strange formations of calcium carbonate that cavers refer to as angel wings, columns, straws and ice cream falls, according to their appearance. Brendan reminded us to touch nothing, as oil from human fingers halts the calcification process and stops the incredibly slow growth of the magnificent underground features.

We sat down at one point and turned off our helmet lights to experience perfect darkness, the kind of darkness where you cannot see your hand in front of your face. It was incredible knowing that our waving fingers were out there, but not being able to see them at all.

We then ventured to an area with a pool of water. The cave’s roof was low here and we were able to walk right under some glow-worms. The kids were awestruck, as we could have reached up to touch their long sparkling strings that looked like diamond necklaces swaying in the light emanating from our helmets. Glow-worms have bodies that are only about two centimetres long. They attach themselves to the ceilings of caves and excrete a mucus string 10 to 20 cm long in order to catch insects to eat. Their bottoms glow with phosphorescence to attract their prey: the stronger the light, the hungrier the glow-worm. When the cave floods, they are attached firmly enough to the rock to hold on and wait until the water subsides.

After some serious spelunking, it was time for a relaxing drift on our inner tubes. We set the tubes into the pool of water, sat in them backward and, with Brendan steering, formed a five-person floating chain by interlocking arms and legs. We drifted into deep water and turned off our helmet lights, while thousands of glow-worms twinkled in the high grottoes above us. It seemed like we were looking at the cosmos from an underground observatory — such peaceful beauty in the pitch-black darkness, with only the occasional lonely sound of dripping water.

Eventually, daylight intruded on our starry ride and we left the cave system to rejoin the Nile River in the rainforest. As we were well ahead of schedule, Brendan decided to take Team Canada for some further New Zealand adventure: cliff jumping. The rock jutted about two metres above the water and Brendan explained the levels of difficulty for our next challenge.

Level 1 involved holding your inner tube to your backside and jumping into the water, landing sitting in the tube. Level 2 meant throwing the tube into the water first, then jumping into it to land in a sitting position. We were all able to accomplish Levels 1 and 2 easily. Level 3 was where I dropped out of the challenge, as I knew I would never be able to hold the inner tube to my backside, execute a front flip and land in the water in a sitting position. This was the perfect time to volunteer to be the group photographer.

Everyone else mastered Level 3, so Brendan introduced Level 4 as throwing the inner tube into the water first and then landing a front flip. My son backed out at this point, but my daredevil husband and daughter continued undaunted. They landed this trick a couple of times, albeit sideways. Brendan was the only one to achieve Level 5, a standing backflip into the tube in the water. According to local lore, only one fellow from the circus had ever achieved Level 6, some kind of running back-flip manoeuvre that made us dizzy just thinking about it.

The Black Sheep then made their appearance at the cave exit and joined us to float back down the river in the gentle whitewater rapids. Adults had to push themselves up on their tubes a bit to keep their backsides from getting “river rash,” which occurs when your rear is bruised and banged by rocks. We drifted and paddled back to the starting point, returned our tubes and changed back into our street clothes. Three hours had flown by, so we ate our lunches on the train as it chugged back through the tropical forest. Our adventure was complete with complimentary photograph souvenirs and a final treat of hot chocolate with whipped cream, New Zealand-style.

Pack your bags

MEMORABLE MOMENT

The breathtaking beauty of drifting through the darkness under thousands of glow-worms together as a family.

STRESS FACTOR

We were on the lookout for giant eels after our tour guide told us that just the week before, he had been frightened by a 10-foot-long black eel waiting in the water near the cave exit. Thankfully, we never saw any eels on our adventure.

GETTING THERE

Air New Zealand: 310-615-1111; http://www.airnewzealand.com. Offers daily flights from Los Angeles.

WHERE TO STAY

Chelsea Gateway Motor Lodge Westport: 330 Palmerston St., Westport, New Zealand; 011 64 3 789 6835; chelseagateway@xtra.co.nz;http://www.chelseagateway.co.nz. Rates average $115 per night for a two bedroom unit

THINGS TO DO

Norwest Adventures Ltd. 182 Queen St., Westport; 011 64 3 789 6686; norwest@xtra.co.nz; http://www.caverafting.com.

Originally published in The Globe and Mail Travel, Saturday, January 6, 2007