Argentina: Into no man's land

Six days of my life are officially unaccounted for. On examining my passport, a keen-eyed immigration officer might notice that between one exit stamp for Chile and the following entry stamp for Argentina, almost a week is 'missing'. But this is what happened when I took on the Andes, the second highest mountain range in the world. When you're in their innermost depths, you find yourself, in a sense, in no man's land. These enormous peaks may have political borders clearly defined on paper, but with their colossal heights and wildly fluctuating weather, they remain fundamentally beyond anyone's control.

My week was 'lost' when I tried to cross the Andes on horseback. I'd come to trace the route of José de San Martín, the Argentinian general who liberated Chile from the Spanish almost 200 years ago, when just 5,000 men acted out a six-pronged attack through various mountain passes. This particular route, which San Martín personally traversed with the biggest group of revolutionaries in tow, was known as 'the impossible pass' And, at the risk of simplifying a hugely celebrated military strategy, the plan succeeded largely because no one thought he was crazy enough to send an army along such a treacherous route.

Today, however, traversing the so-called Paso de Los Patos is distinctly possible. An evolution in packing lists has surely helped: in come the water-purification tablets and thermal undergarments; out go the cannons and cannonballs. We're also a substantially smaller army: 13 travellers, backed up by Argentinian riding company Pioneros, which has already won a battle of its own in securing the nine different government permissions needed to pass through this unofficial but hugely significant border crossing.

It helps that the act of crossing the Paso de Los Patos is considered a patriotic gesture — at least that's what Eduardo Finkel, our guide and Pionero's founder, believes. By special arrangement, two taciturn Chilean officials meet us at our departure point and stamp our passports on a kitchen table. A week later, all being well, we should reappear on the Argentinian side, where the same thing will happen.

Our group assembles in Los Andes, a small Chilean town that stands 50 miles north of Santiago, close to the site of the Battle of Chacabuco, where the two armies clashed on 12 February 1817. From here, we drive to nearby Los Patos, a tiny village in the cactus-covered foothills, where the pass ended for San Martín. "Prepare to leave your comfort zone way behind," says Eduardo.

Having only moderate riding experience, I'm already worried I might be out of my depth. But if I lack confidence in my own skills, I have no such doubts about my group. A small team of huasos (Chilean country horsemen) pack our gear on to mules. Hugo, the head huaso, wearing the traditional wide-brimmed straw hat over his piercing blue eyes, informs me my horse's nickname is No Se Cae A Palos — a colloquial expression meaning 'he won't fall down drunk', which, I suppose, is broadly what you want.

The first day eases us into the adventure, despite a stifling, arid heat hovering above 35C. We follow a dirt road snaking upwards besides the river Rocín. The pink-hued mountains that surround us are immense, although their gentle curves make them seem a little more welcoming than the jagged, snow-capped peaks that lay in wait.

Most of the group are keen riders, but the skill levels vary, from a Scotsman who competes in equestrian sports at an international level to two Russian women who've barely ridden before. I'm allocated a shared tent with a 70-something Australian woman who grew up on a sheep farm. Slightly built, with a long, grey plait and a devilish sense of humour, she's of an age where I'd unquestionably offer her my seat on a busy train. Yet soon we're taking turns thwacking a tent peg into tough ground with a boulder.

We set up camp that night in a small clearing by the river, where the only sound is the rushing water. I collapse in a camp chair for the first of many open-fire barbecues (steak and blood sausage, grilled aubergine, charred onions and crispy-skinned potatoes). The moon is the brightest I've ever seen it, and this, and the cloudless, unpolluted sky, convinces us to abandon our tents and sleep under the stars.

A long way down

The next day we continue to follow the Rocín. According to Eduardo, a GPS would register our entire ride at 112 miles, but this wouldn't take into account the extreme inclines, and constant peaks and troughs. I find an ascent known as El Aletón the most hair-raising of them all. A narrow trail etched into the side of a steep slope, 656ft above a treacherous river, this was said to be where San Martín's army lost a couple of hundred mules. With every step my horse takes, I watch stones come loose beneath his hooves and tumble down the precipice. Only later does Eduardo explain that San Martín's mules were undone by overcrowding. He had thousands of them. We've only got 10 mules and 20 horses. History isn't to be repeated.

Once our adrenalin levels have returned to normal, we set up our second camp at a tiny outpost used by the Carabineros, the Chilean national police. One of the sergeants tells me they're posted here for a month at a time to symbolically defend the border, as well as keep an eye on trespassing animals and people. Occasionally, something interesting happens: recently, a group of horsemen were intercepted and discovered to be carrying 150kg of cocaine.

Our animals are also subject to border control. When we finally reach the windswept clearing where the two countries meet, there is, of course, no one on duty, only the commemorative busts of San Martín and Chilean independence hero Bernardo O'Higgins. Nonetheless, we play by the rules. Saying goodbye to the huasos and our Chilean horses, we're met by our second support team, led by Argentinian gauchos.

By this point, we're fast gaining altitude and I feel a vice-like headache signal our arrival at 11,483ft. Fortunately, with the help of an acclimatising 'rest day' in Valle Hermoso, it passes relatively quickly. Our tents are dwarfed by wide-open space against the backdrop of Aconcagua, which at almost 23,000ft is the tallest mountain outside of the Himalayas. This majestic dame rises to one side, while to the other is La Ramada, a chain of peaks filled with hammocks of snow. I take photo after photo of the sunset in an effort to properly capture the smoky mauve glow on the rocks and a sun that looks like it's bursting into flames under meringue-like clouds. I fail on every click.

"I've been shopping," announces Eduardo, as we gather that night around the camp table that's reassembled every evening from the various components strapped to a mule. He's carving up a huge chunk of creamy white cheese. Here, in one of the most isolated places imaginable, live a family of goat herders, who'd earlier delivered not only this, but a goat, too, for the barbecue. The next day we visit them in their small house, where a tarpaulin roof is stretched across a short structure of pircas (stone walls with no cement). Carolina, a mother of three, tells us she makes three 5kg cheeses every day. When her husband takes them to market, the horseback trip takes three days.

I think of him the next morning after the temperature once again swings abruptly, from bitterly cold to blisteringly hot. Survival here is tough. In the winter, it's impossible; the nomads have to move on. As we trek, I also can't help but call to mind the 1972 plane crash which left a Uruguayan rugby team stranded in the middle of the Andes for 72 days — they famously survived by eating dead passengers. The crash happened further south and at a colder time of year, but at roughly this altitude. At the end of the 1993 film adaptation, Alive, two of the team finally happen across a lone horseman in an oasis-like riverside spot. I picture the goat herder finding them at one of the more hospitable valleys we passed, where the river weaves through spongy, luminous green yareta plants.

The Valley of the Ducks

We cross into Valle De Los Patos, which means Valley of the Ducks — a name that rather undermines its sweeping majesty. The condors circling above do their best to add drama, only to have their work undone by the almost-comical silhouettes of guanacos (South American camels) dotting the hillside. We ride for six hours with no break. Lunch is typically basic (plain rice, tuna, olives); dinner, a wonderfully hearty stew. We wash it down with wine — just to give the proceedings some historical accuracy, the original army brought wine with them to keep up their body temperatures.

Finally, comes the big one — the day we tackle Espinacito Pass at 14,764ft. I'm not entirely sure what to expect, other than cold weather: out come the down jackets, scarves and gloves. Then up we go, single file on an ever-rising path, which switches back and forth before a final stretch along the side of a steep cliff. The air is thin and I can feel my horse's lungs inflating beneath my calves. A prior visitor to the pass appears to have dropped a pack of pasta, which has cascaded down the hillside. Feeling slightly sick from vertigo and not wanting to meet the same fate as the fusilli, I can barely look at the drop.

But every so often, I brave it. You have to. It had taken days to get here, and this is our reward — one of the best panoramas I expect to ever see. The mountains are at their most indomitable, sprawling out for miles and miles. To the south stands Aconcagua, only its tip obscured by the weather. It feels surreal to be above so many clouds, looking down at the shadows they cast, which adds more depth to the rich spectrum of pinks and purples.

As we reach the summit, it starts to snow. The cold numbs my ears and fingertips. Then a clap of thunder echoes behind us. We gather ourselves quickly to beat the impending storm. We escape the worst of it, despite the gusts that billow the sides of the tent that night to the sound of lightning nearby.

The final day seems almost serene. We plod through prickly, yellow-flowered acerillo bushes and craggy, Arizona-like red rocks. The snowy peaks are still there, but receding. As we finally reach the row of poplar trees we'd been moving towards for what seemed like hours, we find our finishing post at a rural stable. I did it! I loved it, but my goodness, was I ready to be on my own two feet again.

After the Argentinian military officially stamps us into the country, the minor aches soon dissipate, aided no doubt by a shower and hotel bed. As an end-of-ride treat, we're transported the next day to the vineyards of Mendoza for a very welcome lunch at Club Tapiz, a high-end hotel in an 1890s Italianate villa.

Sipping a chilled glass of local Torrontés wine, I'm struck by how readily I'm welcoming back life's little comforts. For Eduardo, it's not so simple. "Your values change in the Andes," he philosophises. "You're living in an environment where things you thought were important aren't important at all. It doesn't matter who's president; your iPhone can't save you."

Crossing the Andes on horseback may not be everyone's idea of a relaxing holiday, but it's the perfect adventure for escapists. Prior to setting off on his historic expedition, San Martín wrote in a letter to a friend: 'What stops me from sleeping is not the ability of the opposition to become my enemies, but getting across these immense mountains.' True, I was greeted with red wine not raised bayonets. But I could still relate.

Essentials

Getting there
The trip starts in Santiago, Chile and ends in Mendoza, Argentina. After the ride, you can transfer from Mendoza back to Santiago, or fly on to Buenos Aires, Argentina. No airlines fly non-stop to Santiago from the UK, while only British Airways serves Buenos Aires with non-stop flights, out of Heathrow. Several airlines service both Santiago and Buenos Aires indirectly.
Average flight time: Approx 20h.

When to go
Crossing the Andes via Paso de Los Patos is only possible in the height of the Southern Hemisphere's summer. Trips are usually limited to January and February. Pack for all seasons, as day temperatures rise high above 30C, but nights can drop to below zero.

Need to know
Visas: UK passport holders don't need visas for Chile or Argentina.
Currency: Chilean pesos (CLP). £1 =1,023CLP.
Argentinian pesos (ARS). £1 = 21ARS.
International dial code: 00 56 (Chile). 00 54 (Argentina).
Time: GMT – 3.

More info
Miracle in the Andes, by Nando Parrado RRP: £8.99 (Orion)
Between Extremes: A Journey Beyond Imagination, by Brian Keenan and John McCarthy. RRP: £8.99 (Black Swan)

How to do it
Equus Journeys offers an 11-day trip to Chile and Argentina, traversing the Paso de Los Patos crossing with Pioneros. The trip costs from £2,278 per person and includes seven days' riding, meals, guides, transfers, camping and hotels. Excludes flights. The next scheduled trips begin in Santiago on 28 Dec 2016, 15 Jan 2017 and, for the bicentenary, 20 Feb 2017.

Journey Latin America has a 10-day trip to Chile and Argentina, visiting Santiago, Mendoza and Buenos Aires, starting from £3,764 per person. Includes flights, transfers, hotels and breakfast, plus full board with wine during a three-night stay at Cavas Wine Lodge, where short horse-riding trips can be arranged.

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Published in the June 2016 issue of National Geographic Traveller (UK)