Calder swims across France

You will search in vain in your French phrasebook for: "Madame, why may I not wear these perfectly decent Marks & Spencer swimming trunks in your fine pool?" Also missing is: "Does anyone know any shops around here that sell bathing caps?" The suffocating blanket of heat that seems to smother France from Bastille Day onwards is getting to me. I am starting to sweat like a Prestwick air-traffic controller trying to figure out where to slot a couple of deadly weapons consignments among all the Ryanair holiday flights. The Piscine Georges Vallerey, on the north-east edge of Paris, is proving a difficult first stop on a venture to explore the great bathing locations of France.

Earlier this month, the actor David Walliams swam across the Channel to France; I intend to go one better and swim across France, picking out the best places to cool off this summer. But life is going even worse than usual.

I arrived at the pool half-an-hour ago and expected by now to be splashing happily in the water where once Tarzan triumphed. I had reckoned without the perverse etiquette of French natation. Apparently, my baggy shorts may harbour dangers to public health. And as for my hair...

Tarzan, or at least the actor who played him, surely never had this trouble. Before Johnny Weissmuller went to Hollywood, he was an Olympic champion. He collected gold for the 100m and 400m freestyle at this very pool, built for the 1924 Paris Olympiad. Now that the pool named for a French champion swimmer has reverted to a municipal facility, personal hygiene stands in the way of piscatorial prowess.

As the story on the previous page explains, France has a big problem. Relative to its size and population, it has far too little seashore. You may have an image of blissful shores from Brittany in the north-west to the Côte d'Azur in the south-east. Yet France is way down the league in terms of millimetres-of-shore-per-citizen. Last weekend, the national news focused on Strasbourg: the most landlocked of French cities is 450km from open water. The nearest shore is at Zeebrugge in Belgium, with the Italian Riviera slightly further away. So rivers, lakes and quarries are pressed into summertime service, supplemented by a formidable range of pools with an even more formidable range of staff.

Happily, someone points to a vending machine at the Piscine Georges Vallerey; it promises neither coffee nor chocolate but "vos achats de natation". Unhappily, the largest denomination of note it accepts is €10. No, says the stern lady at the till who had tutted as she inspected my shorts and jabbed at the sign warning bonnet obligatoire, she does not have change. So I walk down to the Franprix shop and buy a couple of things I do not need in order to get the change to buy a couple of things that are crucial to my immediate plans: a pair of black trunks that are suitably, er, figure-hugging, and a natty blue and white bathing cap.

In the changing rooms, you are instructed to insert a 10-franc coin to persuade the locker to lock. This is a challenge now that the euro is in its fifth year. A 50c coin seems to do the trick. Finally, syncronised with the swimming pool regulations, I am ready to take the plunge - or, to obey the rules, gingerly descend the steps to this vast (50m-long) pool.

As you let the water take your weight and wrap you in a certain serenity, the pool looks enthralling. More of a water-filled aircraft hangar if you ask me, and a very elegant one at that. When it was renovated in 1989, the Twenties style was maintained but a retracting roof was fitted - making it semi-open-air, with half of each length bathed in sun. A shoal of sunbathers pose in their Speedo finery on the tiles around the edge. With a combination of cool water, warm air and reflections of the palest blue dappled everywhere, this is surely the holiday camp for heaven. Above the pool there is a bar where, as you would expect, smoking is forbidden. So, too, is eating and drinking, since the bar is unstaffed and unprovisioned. But at least bathing is allowed, which is more than can be said for my next stop.

Simone de Beauvoir would no doubt be philosophical about the Parisian project that bears her name. First, the new footbridge over the Seine in the east of the capital had to close because of the wobbles. Next, the handy booklet, Nager à Paris, promises that the Piscine Seine-Est, part of the same project named for the companion of Jean-Paul Sartre, would open to the world on 6 July. It did, but promptly closed because of problems with poorly applied tiles (perhaps they should have employed Polish plumbers). So when I crossed the river to the shadow of the Bibliothèque Nationale on the Left Bank, I was welcomed by some friendly staff who told me, very politely, to go away. Since my visit, the pool is now ready for bathers - but attention has shifted to Paris-Plage, the ersatz beach that has enlivened the French capital for five summers. A 2km stretch of the Right Bank of the Seine between the Louvre and the Pont de Sully has been commandeered for holidaymakers with the help of 2,000 tons of sand, this year with a Polynesian flavour. You can observe Jean-Honoré Fragonard's 18th-century masterpiece The Bathersin the Louvre, and within a few minutes join the 21st-century sunbathers beside the Seine.

My aim, though, is to do more diving than a Portuguese footballer as I follow an arc from Paris to the southernmost beach in mainland France. With my posing pouch - sorry, newly acquired trunks - and bonnet safe in my backpack, I venture south on the train for an hour to one of the great rivers of France.

The closest that the Loire gets to Paris is Orléans - a handsome city whose status as the birthplace of Joan of Arc elevates it in the French psyche. The lady at the tourist office across from the cathedral has some more bad news. "We don't have any beaches near here," she says, reaching for a map of the Atlantic coast. With gentle prompting, though, she directs me to the river beach just upstream. As I wander beside the Loire, I wonder if the legendary liberator had bathed in the waters that descend in a delicious arc from the Massif Central to the Atlantic. And then I ponder what to do with my worldly goods while I take a dip.

Abdel and Katya solve that problem. "Have you got €2 for a drink?" enquires Katya, as soon as I laid out my towel next to them. Bien sûr, I reply, so long as you keep an eye on the laptop, camera, tickets, passport, cash and irreplaceable memories in my bag (actually, I am not quite that specific). While I change, Abdel tells me how difficult life in France has become as he basks beneath a benevolent sun that seems to refute every word.

Could I swim from the Left Bank to the Right of the Loire? No. While I am not a weak swimmer, the rules here - enforced by a lifeguard perched beneath a yellow parasol - insist that you remain within closely defined boundaries. To stray beyond the line of buoys provokes a whistle, so instead I splashed around with a group of Algerian boys as we argued about Zidane's sending-off in the World Cup final.

Refreshed, I drift along the road to an even more tempting river, the Loiret. In the village of Olivet, just south of Orléans, it flows past a quintessential French riverside scene: villas with gardens running down to the water, and restaurants that demand you to sit down, sip an aperitif and inhale the delicious drowsiness of high summer in France.

The journey south from Orléans comprises idealised French campagne. Crew-cut wheatfields unravel across the hills, the view interspersed with oddities: between the railway and the highway, which entwine for hundreds of kilometres as they race south, stands a random collection of hedgerows, sticking up like odd teeth in a dentally challenged jaw.

The closer you get to the Mediterranean, the more intense the summer becomes. Dusty railway stations serve villages whose terracotta-to-honey colours have a sun-bleached look about them. Only the robustly buttressed churches seem to standing up to the heat - until Ambazac station, where someone keeps the hedges clipped with military precision and ensures the flowers in the neatly kept beds display primary colours beneath the most mighty sun. But by the time I reach Cahors, I am wilting. The Lot looks inviting, but interdit. The Romans came here two millennia ago to bathe in the spring waters, and built a pool dedicated to Diana; only the crumbling façade still stands. So, instead, I get on a bike and head upriver.

The road harmoniously follows the meanders of the Lot. Sunflowers grin at anyone who will notice, buttercups drink in the sun and butterflies flutter by on the lightest of breezes. Crikey: the heat must be getting to me. I must cool off. In the cheerfully named village of Bouziès, I spy a hotel swimming pool. How much, I demand of the receptionist at the Hôtel Les Falaises, must I pay to take a dip? It turns out that non-residents can swim for the price of a drink at the poolside bar. Despite the name of the village, I stay off the booze. A grande crème costs the same €2.60 as the swimming pool in Paris, but it is served with a smile and earns a tip. This elicits the information that the latest property spending spree for the British is to buy up the Lot. The no-baggy-swimming-shorts rule still applies, but bonnets are optional - and diving is permitted. * * Diving into the Célé, which splits from the Lot just upriver, is tempting but reckless: this 40km-long wriggly swimming pool is a shallow and sometimes fast-moving river, and extremely popular with bathers and kayakers, as it carves through monumentally pretty countryside.

Like baking bread, gently roasting terrain gives off a heavenly aroma. The same cannot be said for me when I stop off at the refuge at Espagnac, built for the pilgrims on the long and winding path to Santiago de Compostela. Through a fence, I see a pool so perfect and empty that it looks irresistible - but it is defiantly privée. Along the river in Figeac, the Hôtel des Bains has a tempting name, yet the only baths are in the rooms. So, instead, I continue to Toulouse, and check into the Polar Bear Hotel to chill out and enjoy the sauna and Jacuzzi promised in my brand-new guidebook. Sadly, the facilities at the Hôtel Ours Blanc were scrapped in renovations several years ago.

I have been tempted to Toulouse by the prospect of the newest city beach - a trend that began in France a decade ago and is spreading rapidly. This year, Toulouse has joined the beach club, but the results are far from inspiring. Imagine trying to create an urban beach amid the huge sprawl of the NEC in Birmingham. That is exactly what the city of Toulouse has done in the Parc des Expositions. Bringing in a few truckloads of sand and some plastic chairs and tables is not enough. Thank goodness France's finest swimming pool is just across the car park.

Toulouse is home to the world's biggest airliner, the Airbus A380, and also what must be the planet's largest piscine. The main municipal pool is the size of a football field, with a couple of add-ons for good measure. Roses bloom in flowerbeds around the pool, shaded by blossoming trees.

At 10.13am, as I begin my long and inadvertently winding backstroke to the other end of the pool, an A380 on a test flight flew over to the south-west. This is an aircraft that will turn heads. But my head, as it splashes westwards, is full of yet more rules. Besides all the usual interdictions, this is the first swimming location helpfully to point out that it is forbidden to spit or urinate in the water. And submersion is out, too: "La plongée statique ou en mouvement est strictement interdite". There goes my plan to swim end-to-end underwater. Even outside the pool, on a scruffy and bumpy patch of gravel, jeux de boules interdits - playing boules is forbidden. But the pool, besides being beautiful, has the closest France gets to a museum of swimming - the entrance hall of the Piscine Nakache, which is the indoor add-on to the trio of outdoor pools. It is named after Alfred Nakache, a champion swimmer who survived deportation to Auschwitz by the Nazis and set a new world record a year after his release.

Now for the swimming train: not a seaside special (though France has plenty of those, unlike us), but the departure from Toulouse that cuts across to the Mediterranean and Narbonne, and then proceeds south by teetering on the edge of the nation. This is a train that glides gracefully along a causeway that slices between saline lakes. No road nor even pathway comes close, as you skim through the middle of the salt lakes that stretch south, protected from the Mediterranean by slender sand bars.

Sea birds are picnicking on a salt lake to the left, a collection of lonely stone huts are to the right, and, up ahead, comes the cement factory to spoil the view. No matter, after a brief halt at Port-la-Nouvelle (the closest the region of Roussillon gets to a Salt Lake City) you get second helpings, this time even better with the kite-surfers in action to your left and the Pyrenees muscling in from the right. One quick segment finds you shooting straight across the sand, on a pencil-thin stripe of railway.

Soon after Perpignan station - described by Salvador Dali as the centre of the Universe - you reach a trio of resorts that meet every need. Argelès-sur-Mer is a jolly, family sort of place where beach football is the order of the day, and pizza and beer the order of the night.

Beyond here the coast suddenly gets wrenched out of its long, flat progress south into a contorted and alluring series of coves. First up is Collioure, where you feel you have stepped into a Fauvist painting. The washing hanging on lines, the pretty jumbles of cottages that have become art galleries, and the ice-creams served up at Le Glacier on the corner of rue de Vauban or carrer del Castell (Catalan is prominent here): all adopt strong primary colours. Even the tourists do their bit, sporting bright greens and yellows and pinks (though the latter colour radiated mainly from the skin of overheated Brits). I am here to see what inspired Matisse and Derain to paint here.

You can do some formal sightseeing in the church, Notre-Dame-des-Anges, which juts out into the harbour. It has an elaborate altar, but disappointingly no shrine to Adjutor, the patron saint of swimming. (Since you ask, he was an 11th-century Norman knight who is said to have swum to freedom after being captured during the First Crusade.) Framed prints of the great artists are splashed around town, showing where they painted particular views; print versions will have to do, because the originals have long gone. For example, Derain's Les Séchage des Voiles is currently in the Pushkin Museum in Moscow where, let's face it, they need all the sunshine they can get.

Collioure to Banyuls takes eight minutes by rail, one-eighth of which is spent in tunnels. Yet it takes in vineyards (surely the closest to the sea, at just a few feet from the water's edge), 1,000m-high mountains, coves lapped by the gentlest of surf and forlorn chapels.. You end up at a cream-and-peach station decked in flowers. But stay on for one more stop to reach the tail end of France, and the brink of Spain's Costa Brava.

At Cerbère, the train-to-plage journey takes four minutes. The beach is gravelly, but wraps itself happily around the last bay in France, and is filled with familes and a remarkable absence of rules and enforcers. At last, nage libre - freestyle. Different strokes for different folks, I guess. Here, where the Med meets the mountains, I float out to sea on my back, look at the Pyrenees, reflect that the water shimmers with the same delicate blue as the pool in Paris, and savour the liberty and fraternity of the open sea.

TRAVELLER'S GUIDE: GETTING THERE

Simon Calder paid £59 for a return ticket on Eurostar (08705 186 186, www.eurostar.com) between London and Paris. A three-day French rail pass costs £117 through a range of agencies.

Paris: The Piscine Georges Vallerey is at 148 avenue Gambetta, metro Porte des Lilas. For opening hours call 00 33 1 40 31 15 20. Entry: €2.60 (£1.85).

The Piscine Est is on the Left Bank on the Quai Francois Mauriac (00 33 1 56 61 96 50). It opens at 10am daily, and closes between 8pm and midnight, depending on the day. Admission is €5 (£3.50) for the first two hours, and €5 (£3.50) for subsequent hours.

Paris-Plage runs until 20 August between the Louvre and the Pont de Sully. The website www.paris.fr gives more details on all Parisian pools in English or French; from the home page, click on Sport.

Orleans: One hour by train from Paris Austerlitz. The beach is at Ile Charlemagne (which is not actually an island) on the Left Bank of the Loire; admission free.

Bouziès: you can swim at the Hôtel Les Falaises (00 33 5 65 31 26 83), beside the river, if you buy a drink at the poolside bar.

Figeac: the riverside Hôtel des Bains, 1 rue du Griffoul (00 33 5 65 34 10 89); doubles from €43 (£31), excluding breakfast.

Toulouse: the Piscine Municipale is on the Ile du Ramier, about 20 minutes' walk from the centre; a free shuttle bus operates from Arènes in the city centre in connection with the Toulouse Plage. The swimming pool opens 10am-8pm daily, admission €2.45 (£1.70). For more information visit www.ot-toulouse.fr.

The writer stayed at the Hôtel de Ours Blanc Centre (00 33 5 61 21 25 97; www.hotel-oursblanc.com), which charges €67 (£48) for a double; breakfast is an extra €7 (£5).

Cahors: the writer stayed at the Hôtel du Terminus (00 33 5 65 53 32 00), which is close to both the railway station and the Baths of Diana; doubles cost around €68 (£50), excluding breakfast.

Cerbère: the writer stayed at the Hôtel La Dorade (00 33 4 68 88 41 93), which charges €55 (£39) for a double with a sea view, with breakfast an extra €6.50 (£4.65).