heat haze dances over the debris on La Réunion's côte sauvage, the wild, undeveloped south of the island. Surveying the ashen and deadened forests from here, a few metres from the waves of the Indian Ocean, you can feel the sun's heat reflecting from the dark blanket of charcoal basalt. It looks like the aftermath of an atomic bomb, and it's quite, quite beautiful, in a dark, otherworldly way.
When Piton de la Fournaise (peak of the furnace), one of the world's most active volcanoes, decides to vent its anger on the island of La Réunion, it produces fresh, stunning volcanic landscapes. These later become a huge attraction for tourists and locals alike, who collect pieces of the porous, glittering rock as souvenirs. These chunks of lava are, in many ways, the perfect memento of a visit to La Réunion, an island that's all about adventure and activity. A fridge magnet in the shape of a margarita just wouldn't seem right – this is a much more elemental place than that.
It's become something of a cliché to call La Réunion a secret island. This little piece of France in the tropics – a short hop from the neighbouring holiday island of Mauritius – is French-governed and uses the euro, and Europeans don't get a stamp in their passport despite having flown for 13 hours. It is a favourite with Parisians, some coming for a fortnight of trekking, others settling for good. And, from this weekend, La Réunion could find itself on many more travellers' maps: it becomes a stop-over destination for European tourists bound for the Antipodes, as Air Austral, the island's own airline, begins a service from the capital, St-Denis, to Sydney. British passengers can join the flight in Paris and break the journey here.
While Mother Nature provides an appropriately exotic backdrop, the French influence on the island makes the quality of life as cosmopolitan and sophisticated as most of Europe: petrol stations stock rows of fine wines, fashion magazines and tins of cassoulet.
On my flight (with Air France, rather than Air Austral) from Paris to St-Denis, I sat next to a Réunionaise businessman who splits his time between the island and New York City. "A lot of Parisians are moving to Réunion," he told me. "It usually takes them three years to decide, but they stay. And after 15 years they call themselves Réunionaise rather than Parisian." Presumably the same people adopt the distinctive Réunionaise accent: bigger, slower, more rounded than it is in the French capital, with a lilt reminiscent of West Indies patois.
While prices on the island are high (shopping clocks in at about 30 per cent more than you'd pay in Paris), the quality of life is excellent, and the natural beauty is astounding. Long stretches of highway are a riot of hot pink blossom. The main geographical highlights lie in the middle of the island: Cilaos, Salazie and Mafate. These are the three cirques, great natural amphitheatres scooped out of the mountains. Journeying through their valleys and cryptomeria forests, whether by foot or car, is wonderful; the land looks as if it has just emerged from the sea, a rugged collection of lush, emerald-green peaks dripping with waterfalls.
The city of St-Denis looks and works like any European urban conurbation, although my flight companion (who grew up in the capital) said with more than an air of ennui that it is "best to be avoided". There's certainly little here to compare with the organic landscape, although the whisper-thin transsexual prostitutes who hang around street corners, legs stretching cartoon-like from micro skirts to towering high heels, are certainly not without colour. Similarly gaudy are the elaborate graffiti adorning the city streets – no dull tagging here; the spray-can art is as urban and involved as anything in New York City.
The place to eat in St-Denis is L'Appart, though its unapologetically avant garde menu is more interesting than accomplished. Chef Aymeric Pataud has a background in aromatherapy and he prepares his dishes by combining essential oils in experimental ways, so a tuna dish comes served in a dessert glass with eucalyptus and banana. It's a culinary adventure in a very sleek, contemporaneously styled dining room that has become a destination in itself. If nothing else, the food certainly makes a change from the vanilla-infused dishes that proliferate in restaurants elsewhere. (Vanilla is to Réunion what the grape is to the Champagne region.)
Vanilla pods aside, the one dish that appears on most menus is the Creole-meets-Indian take on the curry, known as kari which, although milder and more turmeric-infused, isn't in fact all that different from, well, curry.
The Réunionaise eat their evening meal early, at around 7pm, and dinner is all done and dusted by 9pm. Things work to a different timetable here, dictated by the sunrise and by the heavy cloud that rolls in to make many peaks invisible by mid-morning (if you're sight-seeing in the cirques, make sure you get up just before sunrise to make the most of the day).
By 5am, half the island is already awake; the rush hour starts at 6am; and, while this is an island in the Indian Ocean, the peak-time traffic is as frustrating as its counterparts in London or Paris. Cars crawl along the coast road in the morning, edging past the picturesque seaside cemeteries peppered with stark headstones, themselves interspersed with brightly coloured bunches of blooms. Elsewhere, there are impromptu shrines to dead sailors and fishermen; crosses wedged into the rocks next to blowholes in the cliffs close to where they perished. It's enough to remind you that, as French as La Réunion is, this is not the Côte d'Azur.
As you make your way around the coast, the island changes dramatically; the west is sun-drenched and dry, the east is lush and frequently washed by torrents of rain (eight times as much rain falls here as on the western side). As with everything else on La Réunion, the weather is extreme, with wildly differing microclimates: mountain dwellers, I was told, can often accurately predict rainfall (or, at high altitudes, snowfall) in one isolated patch, while saying with some confidence that 300 yards away it will stay dry.
Most tourists to the island come with one thing in mind: trekking. A 45-minute trip by Helilagon helicopter over the three cirques and the active volcano is a popular if expensive option, but to make the most of the landscape you have to engage with it at ground level.
The most spectacular trekking on the island can be found amid the three cirques. The most popular route is the Grande Randonnée Route 1, starting in Cilaos and taking five days. You book your various gîtes online before setting off, then make your way from the 4,000ft summit views of Cilaos to Caverne Dufou. From there it's on to Hell-Bourg, an old spa town not so much dwarfed as intimidated by its lush valley sides, via Piton des Neiges, walking along the cirque rim through the Forét de Bélouve, a Lost World fantasia of flora and fauna. From Hell-Bourg you treku oto the often mist-shrouded towns of Grand Ilet and La Nouvelle and then back to Cilaos.
While this isn't harness and hard-hat territory, it's not to be taken lightly – some of the trickier paths are punishing if you aren't fit, and you will need heavy-duty walking boots and appropriate apparel. That said, many of the Réunion regulars take it in their stride; as you stand at the start of the trek to Piton de la Fornaise, many of those starting out on the five-hour hike appear to have all the steely determination of someone popping out to their corner boulangerie for croissants.
Talking of croissants, the Réunionaise obsess about their food in a typically French way. Wandering around the Friday afternoon market along the coast of St-Denis, I bypassed the stalls selling various Réunion-emblazoned T-shirts and shopping bags and instead made for the fruit and vegetables. Rows and rows of vendors had piled up, in the most extravagant and generous of ways, mounds – no, mountains – of spiky pineapples, blood-red chillies and other assorted leafy-green crops. Varieties of vegetable, herb or spice were separated by chaotic flower arrangements; some fruits had been split apart, displaying ripe and colourful innards.
At the weekends, many residents take to the forest-fringed beaches of the south-west coast for elaborate picnics overlooking the black volcanic rock jetties, which roll like Cubist-painted fingers into the sea. In the evening, the main thoroughfares of St-Gilles, 25 miles westwards along the coast from St-Denis and home to most of the larger hotels and the island's nightlife, are awash with beautiful young things en route to pizzerias. Meanwhile, in the cirques, hikers dine table d'hôte-style at the small independent hotels.
There are no chain hotels on La Réunion, either in the mountains or on the coast. Instead, there are places such as the candy-coloured chalets at the cute-as-a-button Jardin d'Héva in Hell-Bourg, where I stayed, surrounded on all sides by emerald mountains that disappear as if without summit into the clouds, or the chic three-star Iloha near St-Leu, all thatch and colonial accents. Alternatively, there's the Iloha's sister hotel, the Palm Hotel & Spa, in Grand Anse on the south coast which, with its minimalist, glossy styling and infinity pool clearly designed with swimwear shoots in mind, is bringing a bit of Mauritian beach-resort style to the island.
The bulk of the rest of the hotel accommodation on the island is still good, if sometimes basic, and in spite of the punishing euro exchange rate, the prices are on the whole pretty reasonable for the middle of the Indian Ocean: £100 a night gets you two stars, £200 gets you four, half board. This isn't, for the moment at least, a place primarily concerned with resort life; it's a place for getting out there and doing it all.
The beaches on La Réunion do not have the same magic as the bleached white sand and turquoise coral lagoons of nearby Mauritius. To make the most of the ocean here, you should try your hand at surfing off the coast of St-Leu, halfway down the west coast. If that sounds daunting, then take a walk through the neighbouring botanical garden, with its acres of outlandish cacti that form sculptural porticos and thorny, Gaudi-like fences; you'll see a seemingly endless procession of paragliders catching thermals and descending from the cliffs above you.
Piton de la Fornaise is undoubtedly La Réunion's star attraction. As you drive along the Route Forestiére du Volcan, climbing to the summit, you rise through iron-ore-striped hills and then descend to the Plaine des Sables, the flattest, widest, smoothest, deadest space on the island. On your way down to this Martian expanse, you see a constantly smoking trail of red-brown dust thrown up by cars en route to Fournaise in the distance. It's the only visual ripple in an otherwise eerily smooth vista. Further on, as you climb higher to the volcano's summit, the landscape becomes moss-green again, littered with peculiar bushes with clusters of vertically grouped branches that look like polished bone, all bald and marble grey. There are picnic spots here, above the clouds, complete with tables and chairs, perfect for feeling like you're having lunch on another planet.
When you finally park at the summit, alight and walk to the rim, where you can gaze down into La Fournaise's crater – the still-rumbling stomach of the island. It takes some time to work out what you're seeing: to the left is a cinder cone, smooth as a snow drift. At first, it looks to be perhaps 100 yards across, dwarfed by the rest of the crater. Then you realise that the almost imperceptible black dots moving around it are people who have trekked down to the crater's surface, and you've got the scale totally, wildly wrong. Everything you're looking at is infinitely more vast, infinitely more impressive – a humbling but profoundly moving realisation.
The writer flew to La Réunion with Air France (0870 142 4343; airfrance.co.uk), which flies from London City to La Réunion via Paris Orly.
Flights are also available from Paris Charles de Gaulle with Air Austral (air-austral.com).
To reduce the impact on the environment, you can buy an "offset" through Abta's Reduce My Footprint initiative (020-3117 0500; www.reducemyfootprint.travel).
Helilagon (00 262 2 62 55 55 55; helilagon.com) offers 45-minute helicopter trips over the cirques and the active volcano; €285 per person.
Iloha Hotel, Pointe des Chateaux (00 262 2 62 34 89 90; www. iloha.fr). Cottages start at €108, self-catering.
Les Jardins d'Héva, 16, rue Lacaussade, Hell-Bourg (00 262 2 62 47 87; hotels.ile-delareunion.com). Doubles start at €84 with breakfast.
The Palm Hotel & Spa, Grand'Anse, Petite Ile (00 262 2 62 56 30 30; palm.re). Doubles start at €189, with breakfast.
To pre-book gîtes in the cirques, visit www.reunion-nature.com
Eating & drinking there
L'Appart, 84 rue La Bourdonnais, St-Denis (00 262 2 62 21 01 21).
La Réunion Tourism: 00 262 2 62 21 00 41; la-reunion-tourisme.com