Many would argue that the French are the world’s best connoisseurs and masters of detail. If you need evidence, look no further than the baguettes, butter, and jam, the café au lait, the vintage wines, and the luxury fashion brands.

But there are certain French peccadilloes that are bound to leave the unconvinced slightly dumbfounded and asking themselves, Really? For instance, one of the finest swimwear brands, Vilebrequin, is made in France (though it now happens to be owned by an American buyout firm). The bathing suits are well made, stylish, and can take a beating. They’re also not cheap—at the Manhattan store, on Madison Avenue, a men’s swimsuit costs around $325. No surprise, the brand’s trunks are a big hit on the beaches of St. Tropez, Cap d’Antibes, Palm Beach, and Sagaponack.

The odd thing is, you can’t wear a pair of Vilebrequin swim trunks in a public or quasi-public (e.g., hotel or spa) swimming pool anywhere in France. In fact, a man can’t wear any brand of swim trunks at a public pool in France due to an archaic French law, circa 1903, that requires male bathers to wear what the French call “boxers.”

“Boxers” is a generous description for this rather revealing and decidedly unflattering—unless you are a seriously buff 25-year-old—piece of equipment. Baggy board shorts, as one might find in, say, Santa Monica, these certainly are not. French swimming “boxers” are more akin to an immodest Speedo that’s sheer enough to reveal religious affiliations.

The law is well known, if somewhat reviled, among the French, which may explain why it is not broadcast outside the country. In any event, I learned the hard way.

In Brittany earlier this fall, my wife and I were staying at a seaside spa resort on the northern coast of the peninsula. After a rejuvenating jog on the first day, I walked about half a mile out onto the beach to meet the surf and take a swim in the cool, salty water. Then I headed back to the spa’s hot tub to warm up, clad in my T-shirt and Vilebrequin swimsuit. Nobody noticed me. I saw that others were wearing their spa-issued bathrobes but paid them no mind. Usually in these situations, at least in America, there are plenty of plush, high-thread-count towels near the pool area. Not in France, apparently. I looked in the men’s locker room. No towels there either. I returned to the front desk. Tactical error. No towels there either.

But then I got an earful about my numerous transgressions. First, I was supposed to have worn the spa-issued bathrobe, found in my room, down to the spa area. I was also supposed to have brought the turquoise-colored, doily-size towel with me. And then, the pièce de résistance: I was not allowed to wear my French-made Vilebrequin bathing suit in the hot tub or pool.

Apparently, such swimwear is considered unhygienic in France, due to the peculiarities of the male anatomy, and the tendency of men to wear their bathing suits all day long, collecting dust particles and other bacteria that are liable to end up in French swimming pools. Do not despair too much; these rules apply only to men. In France (and maybe everywhere), women are considered inherently more hygienic.

Anyway, the spa attendant said she would be happy to sell me a pair of the required “boxers,” which she promptly pulled out to show me in all their skimpy glory. Or at least that’s what I think she said. Another interpretation was that she would let me borrow a used pair of the boxers for free. Either way, I decided to pass.

By this time, a small group of spa-bathrobe-clad men had gathered around me to deliver a knowing Gallic look of disdain, as if to say, “What the hell were you thinking trying to swim in a public pool without the appropriate kit?”

The whole charade left me confused. Last time I checked, public-pool aficionados in America were not experiencing a breakout of infections, and one must believe that the chlorine count is high enough both in America and in France to wipe out any bacteria. Nevertheless, the need for men to wear “hygienic” swimsuits in France is widely accepted, if not necessarily applauded.

Woe unto those who have dared to repeal the law. In May 2022, the city council in the French city of Grenoble voted to loosen the restrictions on what can be worn in its swimming pools, only to find that the French national government objected and the regional government authorities cut some funding to Grenoble. Go figure.

As much as I love France—the people, the food, the countryside, the history, the seemingly effortless knowledge of what’s truly important in life—this quirk really had me scratching my head. Meanwhile, don’t even get me started on the showers, what with the degree in physics needed to turn them on and get the temperature right—and that’s to say nothing about the lack of water pressure. What the heck is up with these French and water, anyway?

William D. Cohan is a Writer at Large at AIR MAIL and the author of such best-selling books as The Last Tycoons, House of Cards, and The Price of Silence. He is a founding partner of Puck. His latest book, Power Failure, is out now