Waking up to a rainy Rotorua, we rolled out of town and on through 3 hours of sheep-filled fields to the west coast to visit the Waitomo Caves.

Traditionally used as burial places for Maori chiefs, the limestone caves on the west coast had been mostly forgotten until recently when some avid cavers persuaded the land-owning farmers of their money-earning potential. Waitomo is the most famous of these accessible caves, its glow-worm covered cavities and fast flowing underground rivers making it the ideal location for some more kiwi adventure tourism. We chose the more tame Blackwater Tubing option, which we understood as gently floating down an underwater river seated on giant inner tubes, underneath a constellation of glow-worms. This was one element of the tour...

Our guide Brad was in his early twenties and sported a weird half-shaved / half-mullet haircut. As we got kitted up he regaled us with tales of his adventures with his caving-buddies, including one trip where they spent four days underground exploring a cave on the south island. Clearly a strange kid, he also seemed to suffer from a kiwi version of tourrettes, whereby he randomly punctuated his sentences with the word 'Sweet!', exclaimed at a high-pitch: 'Yep, just grab yourself a wetsuit there... Sweet! And get yourself a helmet SweetSweet! And we'll be getting down the caves SWEET!'

Of course it wouldn't be a kiwi activity if it didn't involve some kind of adrenaline rush. Blackwater Tubing delivers this by jumping backwards off underground waterfalls. Sarah did not look pleased when this part of the tour was explained to her. The jumping backwards thing is apparently risky enough to warrant a practice run. Dressed in wetsuits and crash helmets, and carrying our inner tubes, we waddled to a nearby stream where each of our group took turns to jump in, make a big splash, then paddle with the current to the side to climb out. When it came to Sarah's turn however, the cold water clearly induced some kind of shock, causing her to forget how to paddle completely. She was quickly taken by the current and carried downstream past the point where we were meant to climb out. Heroically, I dived back into the river to grab her just before she disappeared from sight, and towed her to safety. This act would have been more impressive had our young guide Brad not then shouted to me 'just put your feet down mate!', at which point I realised the 'river' was only four feet deep.

Anyway, with Sarah less than encouraged by her practice run, we drove to the caves access point and descended into the bowels of the earth. I really enjoyed it. At points we had to lie face down on our inner tubes and float under huge slabs of rock with only a foot of breathing space, and in others the caves opened out into huge caverns where we rode our tubes at pace down torrents of water. The waterfall jumps were awesome, and not nearly as cold as the trial run – after half an hour in cold water we couldn't really feel much colder. I think it's fair to say Sarah didn't like the experience as much, but Brad did a great job in guiding her down safely, and she has conceded that it was worth it in the end when we reached the glow-worm caves and switched off our head torches. By each grabbing the feet of the person behind us, our entire group was able to float down the underground river in a huge chain, everyone staring up at the luminous green lights that plastered the ceiling.