New Zealanders didn't invent adrenaline but, better than anyone else, they've figured how to bottle and sell it. Bungy jumping, the South Island's most dubious contribution to world culture, began near Queenstown and kick-started a whole industry. Kiwi fortunes have been made on the premise that tourists, especially backpackers with under-stimulated "fight-and- flight" systems, will pay good money to dangle at the edge of any virtual abyss, screaming and scared shirtless, as long as reasonably assured they'll be back at the lodge in time for drinks and to flash the trophy photos.
Queenstown has traditionally been the laboratory where Kiwi fiends brewed up new kinds of madness for paying chancers - brushes not so much with death as with life. The North Island heartland town of Rotorua has also moved into the game of selling peak experiences, adding other mutant activities like Shweeb, Zorb and blackwater rafting. I set out to sample some of these self-administered adrenaline spikes.
Leaving the sulphurous vapours of Rotorua city, I start on a fairly conventional whitewater rafting run on the Kaituna River. After a kilometre or so of moderate bouncing through a primal green alley of forests and silver ferns, suddenly "conventional" turns into insane as our big rubber bucket plunges vertically over a waterfall that's billed as "the world's tallest drop in commercial rafting" - some six metres. Whomp! Have a Kaituna cocktail - adrenaline and ice-water, stirred, shaken and agitated. We six paddlers survive even though our guide on the sweep oar is almost pitched overboard.
Drying out, I head for the hills to a kind of insane asylum called Agroventures. First comes a spin on the Shweeb - apparently that's German for "hang, suspended" - a high-tech contraption in which the rider lies supine inside an aluminium and perspex capsule that's suspended from a 200-metre oval metal track. You cycle furiously, horizontally, around the circuit, reaching speeds of up to 45km/h while trying to beat the clock or another Shweeber on a parallel track. After three furious laps of this I emerge with jelly legs that will barely support my stagger to the next event in the Agroventures' stunt-a-thon.
It's called Freefall Xtreme. I prefer "upward sky-diving". You don this strange jumpsuit, mount to the top of a 10-metre wide tower that has a broad circular grill in the middle, then cast yourself horizontally on to the jetstream of air that blasts upwards from the grill. Below is a massive V12 engine powering a fan that generates an updraft sufficient to suspend your body in mid-air. The buffeting sensation is like leaning out of a jumbo jet in mid-flight - Hey, Ma! Look, no parachute! Later, the photos show my face almost peeling off in the wind blast. Not much improvement on normal.
I wobble back down to my next big thrill, the Agrojet. I fear the signwriter missed the second "g" in spelling it. Talk about aggro - this little red rooster is a sawn-off, go-kart-sized jetboat with a Formula One engine on the back. Just two passengers are strapped in to the front seat beside a daredevil who guns the thing full throttle around a small, man-made lake that's studded with islands and chicanes. We go from a standing start to screaming your lungs out in 10 seconds as the hell-driver flings the boat full-speed through flat turns and 360-degree nose-spins.
Thinking that dry terra very firma might be nice for a while, I next investigate the curious activity known as Zorbing. Picture this - a 3.5-metre diameter ball made of thick, clear plastic and, suspended within it, there's a smaller plastic sphere. Wearing just swim shorts, I crawl into the inner sphere through a sort of navel, which is sealed behind me, there to sit in a puddle of water. Now what? This curious orb is perched at the top of a hill, facing a banked, curving pathway. The lad who has imprisoned me in this fiendish apparatus then gives it a shove and I am suddenly rolling, tumbling, bouncing, sloshing, pitching every-which-way for a few hundred metres. It's like being trapped inside King Kong's beachball. When the thing rolls to a halt on flat ground, I wriggle out, almost kissing the earth that I have fallen on to. I congratulate the ingenious Kiwis on having found a way to induce seasickness while dispensing with the unnecessary pleasures of either boat or ocean.
If I didn't feel claustrophobic enough inside that bizarre Zorb-thing, then the thought of plunging into an underground river that runs through pitch-black caverns definitely does the trick. Nevertheless, blackwater rafting it is. With a party of a dozen other cheap- thrillseekers I get kitted out in a thick wetsuit and booties, plus helmet, then handed an inflated truck-sized inner tube. After a few preliminaries we trek through the forest and climb down into a deep limestone fissure. This is it: the river of no return. Following our leader, a bright young Canadian woman called Janna, we leap lemming-like, but backwards - with bums in tyres - into the roaring black abyss. Fortunately there's water down there. On the other hand there's absolutely no light. We switch on our helmet lamps and for the next two hours float for kilometres down this underground Styx, enchanted.
At one point we are 65 metres below ground. Janna tells us to turn off our headlights and look up. Above is a subterranean galaxy, a black velvet Sistine ceiling alive with diamond light - glowworms, Arachnocampa luminosa, by the many thousands. The vision is magical, numinous, even if the scientific explanation is not. Janna explains that glowworms are more akin to maggots and have a life cycle that consists of nine months of snoozing followed by a two-day finale that's best summarised as "eat, shag, expire". Sounds like a backpacker motto.
We emerge exhilarated from the stygian labyrinth into golden forest sunlight. Back at the rafting base, after hot soup, we find photos and videos of our adventure ready for purchase. As in almost every thrill product, merchandising is a major part of the experience. Which raises a modern-day philosophical question: if an adventure goes down in the forest and no camera catches it, did it really happen?
For good reason Rotorua pumps itself as "the beating heart of New Zealand". Its menu of thrill sundaes goes on and on. The ones I want to try but don't have time for include sledging (surfing whitewater rapids on a body-board), mountain biking in Whakarewarewa Forest (the so-called Disneyland of mountain biking), cave abseiling and cave zip-lining.
For my final thrill, I opt for something more sedentary - riding a quad-bike on a safari tour near Port Waikato. I join a small conga line of bikes as we bounce along tracks that weave through high country forests and pastures, climbing to the top of a mountain sacred to Maori, Puke-O-Tahinga. Our genial guide Percy is a Maori farmer and when I ask about his forebears he performs an extraordinary recitation of his family genealogy that goes back 700 years to the arrival of his ancestors on the first great canoes from Raiatea, Tahiti. It's a different kind of thrill to hear this.
The broad, fertile region of Waikato is sometimes described as "like England but with good weather", so it seems fitting that after our quad-bike romp, Percy's wife Nancy serves the most exquisite English teacake, the perfect antidote to an adrenaline overdose.
·John Borthwick travelled courtesy of Tourism New Zealand.
·Rotorua is in the middle of the North Island of New Zealand, 234km south-east of Auckland. There are direct flights from Sydney to both cities. Beside adventure travel Rotorua is famous for hot springs and Maori culture. rotoruanz.com.
·For whitewater rafting, see riverrats.co.nz. For agroventures, go to agroventures.co.nz. Blackwater rafting is at waitomo.com/cave-tubing.aspx. For quad-biking, go to riverlandadventures.co.nz.·There's more information about the Waikato region at hamiltonwaikato.com.
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