UNLIKE the rest of humanity, where the first words uttered from an infant mouth are either “mum” or “dad”, Australian toddlers are likely to first say, “Never trust a Kiwi”. They then develop their vocabulary to such an extent that, by the age of 16, they can fit just about every profanity imaginable within the description of said Kiwi.

Down in the caves of Waitomo — in the very blackest of blackwater, wearing the wettest of wet suits and guided through a labyrinth of underground tunnels by a couple of clearly mad New Zealanders — I began to wonder if the Aussies weren’t right.

“Trust us” they said.

Sitting with a group of about 12 other non-plussed backpackers, taking the Southern Hemisphere’s warm summer rays and lolling on the grass with beers in hand, it seemed that trusting them wasn’t going to be a problem. They had explained what we were going to do and how we were going to do it, so there really wasn’t anything to worry about.

Simple really. We were going to don wetsuits, cover them with knitted jumpers and leggings, walk up a hill, jump headlong into a stream, disappear down a crack in the rock face, and float through a system of caverns that would take us on a fantastic journey underneath the area of Waitomo. Cool huh?

Waitomo used to be a quiet little town about one hour’s drive south of Auckland; it was quite happy being a country town with a few individuals visiting for farm holidays or pony trekking. But then someone decided to exploit the amazing geography of the place and it is becoming a popular site for the backpacking hordes that descend on New Zealand to get their thrills in as many unusual ways as possible.

When the area was formed millions of years ago, it was subjected to unique atmospheric and climatic conditions, the scars of which remain in the shape of unusual geographical features; for miles around there are tunnels, streams, caves, caverns, and drop holes to be explored providing you have the courage.

Visiting the efficient and informative visitors’ centre will quickly set you up for a whole host of things to do — pot-holing, abseiling, rock climbing, canoeing, and blackwater rafting are all possible, and virtually all levels of skill are catered to. I have, in abundance, the requisite skills for blackwater rafting — that is, the ability to cling to an inflatable tractor tyre for dear life, shiver like a ghost, and be very scared all the time — so it was an easy choice.

We all piled into the sunny stream and quickly drifted to the gash in the rock. Once inside, we rafted together in a giant doughnut, turned on our helmet lamps and acclimatised to the surroundings by introducing ourselves, eating sweets and telling jokes.

It was all very peculiar and was, definitely, a unique experience. As we meandered through the caves, the roof changed shape and height every metre. One second it was so high and black that the combined lights of the whole group couldn’t penetrate the darkness; then the next it was virtually touching our heads.

The same thing happened in terms of width as well. When the streams narrowed, we were told to form a snake. Now, what is a simple exercise of getting one behind the other on dry land turned into a frustrating debacle as nobody could control their direction under the influence of a buoyant circle of rubber. It was a minor miracle no one drowned.

Great trust is needed to lie back on the tyre and pass your feet through the arms of the person in front so they can guide you down the squeezes. However, once managed, it becomes very peaceful to just glide around the bends.

Turning our lamps off brought another surprise. The ceilings of these caves around Waitomo are infested with glow-worms. It was amazing to see the roof light up like the Milky Way as we slid beneath it.

At first we didn’t take any notice of a distant, quiet, roaring. Only when we came to the convergence of two underground rivers did we realise the stream we were sculling in fed into a larger one. Not only did it feed into the larger one, it did so from 16 feet up (about five metres). We had to jump and it was virtually pitch black, cold and noisy. However, with no way back, you can either jump or scramble down. After one of us had jumped literally into this sea of darkness, we all followed suit. It was excellent. Then, getting towards the end of the journey, some of us found why we needed the knitted jumpers.

Eels. Loads and loads of eels that nip and bite virgin backpackers’ backsides. Now I knew why there were holes in the wet suit! Apparently they nip and have a nibble, but rarely draw blood. The knitted material is, apparently, too stretchy for the eels to chew through, but it was a little un-nerving to know that what we have on seafood stalls back in Great Britain was finally getting it’s revenge by tearing chunks out of my arse. Thanks Southend! And what a relief it was when the end of the tunnel was seen.

After stripping off our wetsuits and dressing, but still feeling cold, we were offered as much bread, soup, and hot drinks as we needed — this hospitality is very clever as it takes away the physically hard edge to what we had just done. It may not sound a lot — floating around on a tyre for an hour — but if you ask your brain how whacky it was, it’ll be too confused to answer. One thing is for sure; no matter what else you do in NZ, nothing will match the uniqueness of blackwater rafting in Waitomo.