These are some of France's most prized oysters, which grow on some 2,000 acres of fertile oyster parcs, or beds. About 3,000 tons of the mature mollusks and 3 billion seed oysters are harvested from the bay every year. The beds are the private gardens for some 400 small-scale local ostreiculteurs (oystermen), who call themselves, with a Gallic mix of poetry and irony, les paysans de la mer, "the farmers of the sea".

Low tide is the high point of an oysterman's day, and dozens of men and women labor with stooped backs. It's a romantic blend of the bucolic and the nautical. Boats list, dogs splash up and down the mud, seagulls hover like Brueghel crows.

Yves Fauchier, a chest-poking raconteur with a pointed southwestern twang, labors too. Fauchier farms nearly five acres in the bay, and his turf, like that of his colleagues, is clearly demarcated by the gawky sapling poles, which all but disappear at high tide.

He unhooks the rigid metal pouches that confine the mollusks, forcing them to grow in uniform shapes, then turns them over and reattaches them to the racks. "Oysters spend as much time above water as under," he explains. "We turn the pouches to harden the shells, to expose both sides to the air and sun. The harder the shell, the firmer the flesh inside." Fauchier, who learned his trade from his father, also raises oysters in the silt itself—"wild" oysters that are dirtier and harder to purge than their cousins, though some people prefer them.

Fauchier spends the next two hours or so turning his pouches, repairing racks, and shoveling mature silt-buried oysters into crates. Then he loads his boat with a few dozen pouches of oysters. It is a drill he performs once a day—exactly when depends on the tides—in all but the stormiest weather. (Oysters are harvested at between 24 and 30 months of age; Fauchier generally harvests his at 27 months.)

His chores finished, Fauchier dips his leathery hand into a crystalline puddle and scoops out an oyster. "Hungry?" he asks. He pries the mollusk open with a twist of his pocketknife and passes me the bottom half, the oyster spreading, translucent, across the pearly shell. I touch the feathery lip of flesh. It retracts. I tip the oyster into my mouth, crunch once, and swallow. An ocean of salty-sweet juice envelops my tongue. "Oysters are like wine," he proclaims. "They get their flavor from the soil. It's the algae and the silt, the water itself."

We breakfast on a dozen each, then another dozen, as the waters reverse and begin to rise toward our boot tops. In a few hours, these oyster beds will rest under 15 feet of water. When the tide lifts the hull of the boat, we jump on deck and putt-putt toward shore.

We pull up at L'Herbe, perhaps the most typical of the area's dozen or so bayside villages—villages where for the past century oystermen have lived and worked in simple gingerbread cabanes with shutters painted vivid shades of periwinkle, kelp, and lobster red, their clapboard sidings trellised with heavy-blooming vines. L'Herbe is a cultural phenomenon in France, where wooden architecture is rare and such an intimate marriage of work and residential life is even rarer. Fauchier, who was born 50 miles up the coast in the tiny village of Vensac, moved here in 1976, after buying a cabane and oyster beds from a local oysterman's widow. He now runs his business with the help of his nephew, Thierry, and Thierry's wife, Marie-Pierre. As soon as he sees us, the couple's young son, Robin, charges across the sand in rubber boots, shouting, "Uncle, I want to drive!" Fauchier gets the tractor from the garage, hefts Robin next to him, then roars back to the anchored boat to haul the day's oysters up to the processing shed next to his cabane. Nearby, oystermen shout and exchange friendly insults with their neighbors, just a few yards away on either side, as they go back and forth between their cabanes and their boats.

Inside the small shed, equipped with a conveyor-belt sifter that sorts oysters by size and a purging pool filled with continually running filtered seawater from the bay, Marie-Pierre begins to tap apart a clump of wild oysters and scrub them with a wire brush. Nathalie Boydens, another employee, lowers the pouches of oysters straight into the pool, where they will remain for about two days, until all traces of algae and sand are flushed out. (By contrast, wild oysters take about eight days to purge.) The majority of mature Arcachon-raised oysters go to customers in the southwest. Most weekends of the year, Marie-Pierre and Boydens drive to farmers' markets in the Dordogne to sell Fauchier's oysters, which are also distributed in crates marked with his name to Intermarche supermarkets in the region. Anyone wandering by his cabane, however, can stop in and buy the freshest oysters at the best price: about four dollars for a dozen.

Once things are under way in the processing shed, Fauchier turns to me and smiles: "Stay and eat a bite?" Living by the tides, Fauchier leaves the oyster beds when the waters will carry him—which is at a different time each day—and when he gets home, he is hungry. Luckily for him, he is a terrific cook: passionate, spontaneous, and, above all, flexible.

Today, he lights a mound of tinder in the grill behind the shed and throws on some grapevine clippings and coconut-size pinecones. We arrange a dozen or so oysters on the grate. They whiten as they heat up and then slowly gape amid the wispy smoke. Fauchier spoons a bit of white wine into each bottom shell and, like a priest serving communion, hands me one. The oyster tastes of earth and sea. "You can pour in beurre blanc, too," he notes. We also feast on a big batch of wild mussels, which he pulled off the sapling poles while we were on the water, steamed in a fennel-scented court bouillon flecked with bayonne ham.

As we eat, Fauchier tells me more about Arcachon's oyster industry. Earlier, he pointed out neat stacks of terra-cotta roof tiles whitewashed with chalk along the edge of the bay, framing one of the least polluted oyster centers in Europe. These are natural magnets for the microscopic naissain, or fertilized oyster larvae, that floats in the water here, he explains. Oysters are hermaphroditic, generating sperm one year, eggs the next. In the summer, they release their laitance, a milky cloud of spawn, and within 24 hours fertilization occurs. After 20 days, fertilized larvae attach themselves to the tiles and begin to form their adult shells. In a good year, 300 to 500 baby oysters will attach to each tile. The mild, stable temperatures, rich plankton, and gentle tidal exchange between the bay and the open sea pamper them, and they grow strong and well shaped. When they are six to eight months old and each about the size of a fava bean, they are scraped off the tiles like corn from the cob. They are then either transferred to chain-mail pouches or the silt in the bay or shipped to other areas in France or other countries, including Portugal, Ireland, and Morocco, to mature. (The chalk-tile system was developed in the early 19th century by an Arcachon stonecutter named Jean Michelet, who discovered that naissain was not only attracted to chalk-coated tiles but actually thrived on them. This revolutionized the oyster industry. Before then, the only oysters the world knew were the rough-shaped wild ones that cling to rocks and are fiercely difficult to pry off.)

Although all Arcachon-born oysters are members of the species Crassostrea gigas—the hollow-cupped mollusks known in France as creuses—those baby oysters that are relocated to other waters will develop their own flavor, unique to the place where they are raised. Arcachon oysters, for instance, are known for their nutty sweetness; they are also held in such esteem that they are currently in the process of being granted Europe's highest agricultural honor: the Identification Geographique Protegee (IGP), a designation that links a European product with its terroir.

I leave Fauchier's and wander through the dense maze of cabanes, a century of oyster shells crunching underfoot, until I reach the place where I'm staying, the Hotel de la Plage. The hotel and its restaurant, Chez Magne, hark back to the creaky seaside boardinghouses and steamy seafood diners that were once everywhere on this coast but have become increasingly rare since the 1960s. The places of that kind that remain are wildly popular with everyone from blue-blooded Bordelais to Arcachon fishermen.

At Chez Magne, a meal begins with oysters, of course—raw, baked with butter, or served with grilled pork sausages, a classic combination in the region. After that, the fishermen's soup is a good choice. Chez Magne's version contains little more than fish and potatoes thickened with garlic paste and egg yolk and garnished with croutons and grated gruyere. Fish-belly gray and homely as oatmeal, it nonetheless evokes the fresh, mild scent and flavor of the catch of the day.

Chez Magne may be the landmark restaurant in L'Herbe, but the local culinary celebrity is chef Philippe Techoire, who was born and raised in the oyster village of Le Canon—just up the beach from L'Herbe—and who currently presides over two restaurants in Bordeaux, Chez Philippe and Philippe Chez Dubern. Techoire trained at his mother's now defunct restaurant in Le Canon, Chez Irene, and he obviously learned his lessons well. At a small gathering one afternoon at the home of one of his cousins in Le Canon, he expands my knowledge of regional delicacies. His stuffed oysters, flash-roasted with bread crumbs, butter, and garlic until they pop, leave me wiping my chin and asking for more. His oyster fritters are meltingly tender, their coating surprisingly airy. Noticing that he makes a point of tipping out the seawater as he opens each oyster, I gasp. Why would he want to get rid of that precious juice? "That's just the brine," he says, laughing. "You must pour that off. Then the oyster exudes its own juice. That is the best liquid. That you must preserve."

On the last evening of my stay in Arcachon, I stop by Fauchier's cabane for a glass of rose and some more oyster talk. About ten oystermen are still based in L'Herbe and all seem to be doing well, Fauchier tells me, but things are changing. Cabanes are coveted real estate; if one is put up for sale and an oysterman doesn't buy it, by law it must go on the open market, and that is happening more often. Then there is the increasing number of environmental hazards. As the Saint-Tropez of western France, Cap Ferret grows more popular with the yacht set every year. In high season, the bay seethes with noisy and oily pleasure craft that often scrape their hulls on the racked oysters. And the 2002 oil spill from the tanker Prestige, which sank nearby, threatened to snuff out Arcachon's oyster industry altogether. Oyster sales were banned for two weeks until the waters were given a clean bill of health.

Despite these issues, not to mention the long, ever changing hours, there are many reasons Fauchier still loves his metier. "It's the sea, the surroundings," he says. "And it's the nurturing of baby oysters. You seed them, you raise them. We are gardeners. When you put a little plant into the ground, you get a beautiful flower. It's the same for us."

Fauchier does admit, however, that as he ages he dreams of scaling down to minimum production and having a simple oyster stand behind his cabane where he can serve passersby. "A glass of wine, a chunk of bread, butter, lemon, and a dozen oysters," he says. "That's what it's all about."