Day 47, in which we tour the glacier in style

We got up early this morning and commandeered a helicopter to take us to the top of the Fox Glacier. Twelve of us were going up in total, but as helicopters are very small we went in three separate groups and Paul was lucky enough to co-pilot in the front (he thankfully did not need to assume control of the vessel). I sat in the second row, at the back, crammed between the window and an enormous American man.

A helicopter strikes me as a very silly invention. Unlike most flying machines, if a helicopter's engines stall for any reason then you are effectively just sitting in the middle of the sky in a very heavy metal box. At least an aeroplane can glide to safety or a hot air balloon can deflate gently until it lands in a soft grassy meadow. I somehow managed to keep my mind off this topic during the flight, and enjoyed the helicopter ride immensely. We soared close to the top of the rainforest high up in the mountains and plunged down to follow the length of the glacier, which is effectively a long valley filled with heavily compacted and slowly advancing snow. I was surprised by how huge and long it was, although apparently it is only a fraction of the size it was even a few hundred years ago (although it has been growing since 1985).

We then span round at high speed to look at a small waterfall which spirals down one mountain face and onto the glacier, although with all the spinning it was hard to keep track of what we were looking at. The artificial gravity created by the centrifugal force of the turns and the large amount of sky that appeared to be directly below me completely confused my brain into thinking we were flying upside down. I kept my eyes closed during this section but Paul took some good photos of this bit.

Finally, after a sweeping roll round the valley, we landed on a relatively flat bit of glacier where our guide, Cole, issued us with our safety gear. We had already been given lurid red socks and big boots at the helihike centre, and up here we were issued with crampons to tie to our boots and big wooden sticks to aid balance and for probing the odd intriguing crevice. We had to wait for the other two groups to come up, and as the glacier is a dangerous place to amble around we all had to stay put and wait it out. Every time the helicopter came anywhere near us we had to crouch down and face the opposite direction, and even then the blast of the rotors would almost blow us away and we'd be deluged in a shower of loose ice.

The trek around the glacier took around two hours. I was expecting the surface to be fairly smooth and flat, but in fact it was a mass of complex formations. The vast weight of the ice advancing down the mountain causes the surface to fracture and buckle easily, creating compression arches (huge bridges of ice forced up from the surface). Melt water also bores down into the surface, creating huge ice caves when you're lucky and moulins when you're not (a moulin, Cole explained, is when a perfectly vertical shaft is bored into the ice by melt water. He said they are the most dangerous feature on the glacier, since if you fall in you fall until you wedge into the shaft like a cork, and then the melt water keeps coming and you drown. I asked Paul what he thought the second most dangerous thing on the glacier was, and after some thought he responded “stonewashed jeans and matching jacket”).

All of these features are made to look extra amazing as glacial ice – which is denser than frozen water since it comprises extremely compacted snow – filters out all light but for the colour blue, and so these arches and and ice caves have a magical glow about them. We descended into one particularly superb ice cave quite close to where we were dropped off, and then hiked up towards the peak where we found a series of vast compression arches, one of which Paul happily had a scramble through.

Back in town, we went to the only other tourist attraction in Fox Glacier, the café at Matherson Lake, from where amazing views can be had to Mounts Cook and Tasman, the two largest mountains on the island. Alas, clouds spoiled our view of the mountains, while a decerebrate waitress and a toxic US couple at the next table spoiled our enjoyment of lunch.

After a short nap, we walked to the bottom of the Fox Glacier to get the full picture. While the glacier itself doesn't look like much from down here – with its full height and length left to the imagination – it was superb to see the valley through which it had once advanced and was now retreating. We were surprised by the amount of damage something so slow can do to a landscape, with the valley having been completely carved out by the ice and now left as a wasteland of rocks and stones dumped by the glacier in its retreat. There were also lots of new safety signs I haven't seen before – including one which appeared to mean “If you're not hit by a a rockfall, you'll be killed by an avalanche or tidal wave”. Given the Department of Conservation's determination to stop anyone crossing the safety barriers, and the clear message of the consequences, it is hard to believe the young couple who were crushed last year under several hundred tonnes of ice thought that a close-up photo of the glacier was a good idea.

We waited for nightfall with some superb snapper with mango salsa at the Mount Cook Café, and then took an evening stroll through the Minnehaha forest, a short walk through rainforest on the edge of the village. The main attraction here are the glow worms, who lurked in vast clusters on the ferns and moss of the undergrowth. In pitch black, these little white lights looked almost like Christmas tree fairy lights and created an amazing field of stars stretching back into the undergrowth. I expected them to look like the fireflies I've seen in the US – big ugly insects which flashing green bottoms – but they instead burned bright white. We tracked one of the little monsters down on the side of a tree and found they really were ugly brown wriggly worms. No wonder they only try to attract a mate after dark.