Maybe it's living amid mountains famed for cheese. Or perhaps the Alpine air sends locals a bit doolally. Either way, there's some madness afoot in La Plagne. Ten mountain villages make up this scattered resort in the French département of Savoie – and a long and formidable run between them is considered a reasonable idea.
In 2009 it took a (super)man called Patrice Paquier just 12 hours, 32 minutes and 59 seconds to complete the inaugural 110km race. However, my boyfriend and I managed most of that same route, now known as the 6D Trek, in a more leisurely three days – taking time to savour all the glacial gouges, geranium-bright windowboxes and pungent fromageries that Patrice most likely whizzed past without a glance.
La Plagne is primarily a ski destination: from December to April, its 100sq km of slopes draw big crowds, many of them Brits. But in summer, despite the rafting, hiking, biking and climbing options, few tourists visit. Creating and route-mapping the 6D is an attempt to entice them.
We started in Plagne Centre, a 1960s hangover of a place. Our guide was Louisa, a British expatriate who's lived in La Plagne for 20 years. Here, Mont Blanc looms scarily to the north – a forbidding omen. But I needn't have worried. The 6D is designed for all comers. The terrain is hilly, but with well-spaced gîtes, refuges and hotels en route, there's no need to hurry. You can complete the trek in anything from three to seven days.
Despite glorious sunshine, our first steps were underwhelming: Plagne Centre's immediate hillsides were impaled by pylons and maimed by pistes, ugly without a concealment of snow. A truck bounced past, kicking up dust. We followed it to a farmhouse where shelves strained under 40kg rounds of cheese. "It's Beaufort, named after the range opposite," Louisa told us. "Each cheese is date-stamped, then matured for at least five months. The flavour varies week by week, depending on what the cows have eaten."
In summer the cattle graze on high pastures; like them, we headed up, leaving the ski chalets for fields of white daisies, yellow gentians and rocks a-scutter with marmots; hawks and parapenters soared above. By the time we'd dipped down through forest to Champagny-en-Vanoise, the next of the La Plagne villages, things started to feel less ski-scarred and more idyllically Alpine.
The first house we passed as we approached Champagny bore what looked like a Swiss crest: a white cross on a red background. "That's the Savoie flag," Louisa explained. "Some people in Savoie still want independence. In fact, the documents incorporating it into France were never officially ratified – technically it is independent."
Perhaps this rebellious side explains why our 6D signs petered out between the chairlift terminus and the cheese shop. We got briefly lost, righted ourselves, then paused for a picnic feast of bread and Beaufort. After a steep uphill slog, and a descent to the Doron dam, the feel of the Champagny Valley became increasingly off-piste: smaller settlements, wilder mountains, its trough-like glacial groove more obvious – something we learnt more about in Bois, home to the Glacialis Museum.
The valley ended at Refuge du Laisonnay, as did our day. A waterfall tumbled noisily nearby, soon joined by a downpour that transformed the atmosphere: friendly blue skies and awesome mountains looked suddenly menacing under slate-grey gloom. No matter, the old stone refuge was cosiness distilled: hot showers, Savoie wine, candles a-flicker. That night we feasted on crozets (tiny squares of pasta, stodgy with cheese) and spinach-stuffed pormonier sausages. Belly full and dorm mercifully devoid of snorers, I dreamt of Patrice, who would have run all 110km by now. Me? I was glad to have two more days to go.
The next morning, although the sun hadn't penetrated the valley, I had high hopes for a fine day. It was to be a tough one, however: we would be ascending from 1,547m Laisonnay to the 2,652m Col du Palet, deep within Vanoise National Park. The park is a vital sanctuary; ski resorts butt up to its borders but its interior is reserved for Alpine ibex, chamois and hikers.
This was certainly wilder territory, and a lesson in glaciology: we saw ice-strafed boulders, residual moraine, scooped-out mountainsides and, on high, the tongues of numerous glaciers. Grande Casse – at 3,855m the highest peak in the park – lurked behind clouds. It felt positively prehistoric. The clunk of cowbells and whistle of marmots soundtracked our hike to the col, where we quickly dipped down to a refuge, to shelter from the wind and sip coffee in the sun. Louisa knew these valleys almost as well as the bearded vultures circling above: we were not lost.
We were done climbing, though – it was now downhill all the way, via blue-green lakes and Alpine meadows, then waterfalls, larch forest and raspberry bushes, to Rosuel. Here, the refuge was built almost into the hillside as protection against the avalanches that thunder down in winter.
No avalanches to worry about now – just our roommates. Chat over dinner revealed one was prone to "ronfler" – snore. I accepted a slug of Louisa's génépi, her home-brewed liqueur, in the hope it would send me to sleep before him.
It didn't. A cavalcade of ronfler-ing delivered a restless night, which was followed by a chillier morning. Patrice wouldn't have quailed at such things, however, so I toughed up for our final day's hike, along the Peisey Valley to Aime. We passed the neat cottages of Lanche before walking up the Avenue des Mélèzes, a walkway of ancient larches leading to an 18th-century mining school; lead and silver were once extracted from these hills, and this college was one of the country's key centres of underground learning.
We hiked on through earthily pungent forest, then took a short cut in order to make Aime by the day's end. Now outside the national park, ski resorts reasserted their dominance, but the weather picked up and, as our altitude dropped, we were soon strolling amid sunny orchards of fruit trees. As we joined the final stretch alongside the frothy Isère river I thought how Patrice must have wept with joy at its flatness.
The full 6D is a loop, but we chose not to head back to Plagne Centre, and finished in Aime. We browsed its boulangeries and nosed into its 11th-century Basilica Saint-Martin. Then we retired to the Café du Centre. We ordered beers and toasted Patrice – you fit fool! But, really, what's the rush?
The nearest airport to La Plagne with summer services from the UK is Geneva, served from various airports by BA (0844 493 0787; ba.com), easyJet (0843 104 5000; easyJet.com) and Swiss (0845 601 0956; swiss.com).
By train, the journey from London St Pancras is tricky: Eurostar (08432 186 186; eurostar.com) to Paris Gare du Nord – then the TGV to Chambéry and a local train to Aime La Plagne, or a direct night train.
La-plagne.com offers small-group 6D Treks from €440 (£370) per person, including a guide, transfers and half-board in mountain refuges. Flights excluded. Departure dates are 14-18 July and 4-8 August (00 33 4 79 09 79 79; la-plagne.com).
The Araucaria Hotel, Plagne Centre (00 33 4 79 09 20 20; araucaria-hotel.com) re-opens for the summer on 6 July; €68 (£57) double, including breakfast.
Refuge du Laisonnay, Champagny-le-Haut (00 33 6 08 54 34 61; laisonnay.com) has half-board dorm beds from €29.50.
Rosuel Refuge, Peisey Valley (00 33 4 79 07 94 03; refugerosuel.fr), has half-board dorm beds from €36.
The Tourmaline Hotel, Aime La Plagne (00 33 4 79 55 62 93; hotel-tourmaline.com), has doubles from €121, room only.