Travel: Where are you skiing this summer?

New Zealand 1: forget the crowded French Alps. Nothing can beat the drama of Mount Cook.

Bruce was not reassuring. "The crevasses are big enough to swallow up three children in one gulp." Was this a mad idea, to ski en famille down New Zealand's Tasman Glacier? But we had come here, to the remote Southern Alps of South Island, to do just that.

The call had come through while we were having breakfast. "The weather's perfect - we hope to take off in a couple of hours. Can you make it?" I would have felt happier if it hadn't been Friday the 13th. But we'd been thwarted once by bad weather - and who knew what tomorrow would bring? "We'll be there," I assured the pilot.

"There" was a skiing and mountaineering centre in Mount Cook National Park. "We" were a family of five average-ability skiers, the youngest 10, her two brothers a few years older. On a winter-in-August holiday in this multifaceted country, the temptation to "Ski the Tasman" had been irresistible.

To maximise our chances of getting the right weather for the expedition, we'd needed to spend a few days in the Mount Cook area and had opted for a stay on a farm. Bruce and his wife Linda were our hosts on their sheep farm on the shores of Lake Pukaki, over whose still, aquamarine waters loomed Mount Cook's unmistakable triangular peak, Aorangi - "cloud piercer" - to the Maoris. I could see why.

We finished breakfast quickly - eggs brought in warm from the farm by my daughter that morning. Searching the hens' coops for our breakfast was one of her favourite activities. Wasn't she rather small to be exposed to crevasses?

Less than an hour's drive along Highway 80, running between the Ben Ohau range and the western shores of Lake Pukaki, brought us to the mountaineering centre at Mount Cook. Our guide, Ann, was quick to reassure us. There were indeed awesome crevasses, but she knew exactly where they were. "And we'll keep our distance. Do you think you kids can turn their skis well enough to follow close behind me?" We set off for the small airstrip at Mount Cook, where half-a-dozen ski-planes waited on the runway.

The short flight was edge-of-the-seat spectacular. Seemingly close enough to reach out and touch, the dramatic peaks of the Southern Alps towered round the glaciers, rivers of jagged ice tumbling down the valley towards the sea. A detour over the Fox and Franz Josef glaciers and a surprising glimpse of the ocean brought us to Mount Cook. The small cabin was silent with breathless expectation as we prepared to land on the giant natural runway of the Tasman Saddle, the virgin snowfield at the top of the Tasman Glacier. We landed smoothly on the gentle incline. "I thought we were going to fall off the edge," whispered the 10-year-old.

Disembarking into deep snow, we watched with some misgiving as our plane took off through the mountains. We were on our own now, our skis the only option down the glacier. "Come on, you guys, let's go," encouraged Ann. "And try to keep in my tracks; I don't want to be fishing you out of a crevasse." Round-eyed at the thought, my normally wayward children were awed into obedience.

Gliding through the crisp snow on open slopes, surrounded by rugged peaks, the sensation of freedom and space overwhelmed me. The light was dazzling and the air cold on my face. Ice formations had been carved by wind over the years into phantasmagoric shapes. Skis off, we walked in wonderment through a tunnel of startling blue, as if in a magical scene from one of the Narnia books where the White Witch might appear at any minute. To a child's eyes it was immense. "What if we got lost here?" one asked. Stroking the smooth contours of the ice walls, the children discussed the dramatic possibilities of losing their fingers to frost-bite.

The moving tongue of ice on which we were standing was 1,800ft deep in places, with 150ft of new snow compacting every year into yet more ice. Advancing at an astounding 75ft annually, the glacier stretched for 25 miles.

This was a land of superlatives. And of wide-open spaces, inhabited by only three million people but 60 million sheep. I thought back to Bruce and Linda's farm in the Mackenzie Country. In this remote high country, named after a legendary rustler, a sea of yellow tussockland lay in stark contrast to the milky-blue waters of a string of glacier-fed lakes, carved out 17,000 years ago. With the nearest shops 20 miles distant down a rough road, these tough Kiwis lived, Heath-Robinson fashion, in isolated splendour. But romantic expectations of sheep farmers covering their 2,000 acres on horseback were sadly not realised. Prosaic and practical, maybe, but jeeps and trailers were certainly warmer on the cold, frosty mornings when we accompanied the feeding, watching in fascination as thousands of sheep streamed into a snake-like formation, face-to-face alongside the trail of grain.

It felt a long way from the farm now, in the surreal landscape of the glacier. After our detour through the ice cave, we continued in slow, wide arcs through the crunchy snow. The children managed very competently. "My legs are knackered, Mum," was the only complaint. The gradient was not steep, but being more used to the smoothly groomed pistes of the French Alps than the crusty powder, we all took a few undignified tumbles in the snow.

The seven-mile run down the eastern side of the glacier took us a couple of hours. The ski-plane was waiting for us at the bottom, and whisked us up to the Cornice Wall at the top of the glacier. On a snowy plateau amid pinnacles of ice, spread out in the sunshine on a checked tablecloth, was a mouthwatering lunch. Hot soup and glasses of champagne welcomed us, a precociously sybaritic son downing the bubbly with glee. We felt we had cause to celebrate, as we relaxed on makeshift seats of skis and poles in this fairy-tale setting. Life was good.

Then Ann's radio crackled into life. The wind was picking up fast. We needed to reach the bottom, where the plane would collect us, without much delay. The possibility of being stranded there for the night urged us on in a steady progress down the western side of the glacier.

As we flew back across the terminal moraine, a chaotic mass of rocks and boulders, we saw the dust whirling into the air behind us, swept along the valley by the strong wind which was picking up by the minute. We'd made it just in time.

Fact File

Getting there: Flying to New Zealand is now cheaper than ever. Only Air New Zealand (0181-741 2299) flies direct, with daily services from Heathrow to Auckland via Los Angeles. Other airlines fly via intermediate points, ranging from Bangkok to Buenos Aires. Before the end of June, you could pay as little as pounds 600 return.

Who to contact: Alpine Guides offers ski trips on the Tasman Glacier between mid-June and end of September. Alpine Guides, Box 20, Mt Cook Village, South Canterbury, New Zealand, Tel: 00 64 3 435 1834, fax: 00 64 3 435 1898, e-mail: mtcook@ alpineguides.co.nz

More information: New Zealand Tourism Board, New Zealand House, Haymarket, London SW1Y 4TQ (0839 300900, a premium-rate number; fax 0171-839 8929).