Travel: When a rest is as good as a climb

IT WAS the most dangerous section of the mountain. The wind was picking up and we had to negotiate an ice-covered path 2km above the valley floor. The problem was I couldn't seem to trust my legs anymore. I had just climbed to the top of Aconcagua - at almost 7,000m, the highest mountain in the world outside Asia - and I was suffering from the altitude. It wasn't that I'd lost all co-ordination, but I was walking as though I was more than a little tipsy.

Until now, my idea of a hike had been a Sunday afternoon stroll on Hampstead Heath. That's until a mountain-minded friend persuaded me that it was time I attempted something "a little more ambitious".

I began to regret my decision on my very first day in Argentina when, sitting in an elegant Buenos Aires cafe, enjoying a cafe chico and the chatter of Argentine high society, I read that a Czech hiker had died on Aconcagua of altitude sickness.

Two more bodies were brought down the mountain on mules the day before we began the hike. A ferocious storm had struck the highest camp on the mountain, tearing tents apart. Two walkers had been caught unawares and died of hypothermia. Their deaths brought the year's total to five fatalities. Yet 1999 has apparently been a good year.

I'd been warned that there was, on average, one death in 300 climbers on Aconcagua. Compared with other mountains, that's not too dangerous but I was horrified - horrified that I had let myself in for such a perilous enterprise, and appalled by the senseless death of these people. At the same time, though, I'll admit that part of me was excited by this proximity to danger.

The real surprise was just how unexciting most of the hiking up Aconcagua was. This is no soaring cathedral of a mountain but rather a great mass of dark rock circled by sweeping scree slopes. There is a certain magnificence in its bulk, but the attraction is its height and the ease of access. Most of the deaths are down to inexperienced, unguided people being careless. This is - famously - the highest hike in the world. Three thousand visitors a year tread the well-defined path that zigzags up Aconcagua's flank.

But there are still two great challenges in climbing Aconcagua: the altitude and the weather. I had my first taste of altitude after the two- day hike up to base camp; a tent city perched 4,000m up the mountain on the lateral moraine of a glacier. It was a nauseous, detached feeling accompanied by a pounding headache and I felt as if my brain was swelling in my skull, which it probably was.

There's no sure way of avoiding the effects of altitude, but they can be minimised with proper acclimatisation. The climbers' mantra - climb high, sleep low - might be better rephrased as walk a little bit then rest a lot. We had three whole days resting and some days we walked for as little as three hours ... and then rested some more.

I like to rest. The problem is there's not a great deal to do on the lateral moraine of a glacier. There are no plants or animals, just rock and ice and, although the views are stunning, they don't change. I could trace most of the route up the mountain from my tent and, until summit day, wherever we camped we got slight variations of the same view.

Fellow climbers provided an amusing diversion but, compared with typical Aconcagua Man (it's mainly males who climb it), my weekend rambles don't make for good yarns and I was soon ready for a break from all the resting.

Walking at altitude is much like walking elsewhere but it takes much longer and hurts more. We snaked up the mountain like a great long millipede and there was a pleasant hypnotic quality in the steady monotony. I was lucky; I didn't suffer much from the altitude and, weatherwise, we had warm sunny days and, by the standards of Aconcagua, little wind. If you aren't lucky, it can be hell on earth. Winds of 130km per hour are not unusual, and the temperature in summer can fall to -20C, giving a wind chill that doesn't bear thinking about.

Summit day arrived and we set out for the top at 3.30am on a freezing morning. By the time dawn broke we were way above the clouds, above everything. At one point we could see the shadow cast by Aconcagua across what seemed like the entire Andes. As if to compensate for these great views, the hiking got very tough. At these altitudes your muscles get 20-30 per cent of sea-level oxygen and it's very tiring, like a 12-hour marathon but stopping to pant after every step.

Suddenly, though, we were there. For 10 minutes we were on top of the highest of the high Andes with the world stretching away below us. Then the clouds swirled in and we could have been on an icy slab of rock almost anywhere.

Now all we had to do was walk back down. That's when my legs went. The guide tied a rope around my chest and led me down the difficult bit like a dog on a lead. A trifle humiliating, perhaps, but nothing that couldn't be cured by a jolly good rest.

The best time to climb Aconcagua is at the end of December, so now is the time to start preparing. Fly to Santiago, Chile; fares are as low as pounds 400 return, though they rise steeply in December. Next, take a five- hour, pounds 20 bus ride to the Argentine city of Mendoza, to secure the appropriate permit. For more details, consult the `South American Handbook' (Footprint, pounds 22.99)