A fit and ruddy 19-year-old with blond hair and a sheepish smile, James Henderson is tanning on a beach in Magaluf, a town on the Spanish island Mallorca that has long been the destination of choice for young Britons in search of a boozy holiday in the sun. Asked to recount the revelry of the day before, he grins like a man who has just completed a decathlon and is pretty psyched about his performance.

There was a few hours of “pre-drinking,” as he put it, at his hotel, then on to Punta Ballena, a crammed and gritty strip of pubs, tattoo parlors and lap dance emporiums that bursts with action until dawn every summer day. By the time he and his vacation buddy headed to bed, at 3 a.m., they had each knocked back roughly 20 drinks over the course of 15 hours.

“I had a bit of a strange taste in my mouth this morning,” Mr. Henderson said, proudly describing the minimal aftereffects of this marathon, “but nothing too bad.”

Every summer, Magaluf crawls with young British people in search of a bacchanalia, and they find one in what is essentially a slab of the United Kingdom set in the Mediterranean, except seedier than anything in the dingiest corners of London. There are also G-rated home comforts, like kebab shops, Yorkshire pudding and pubs, all at strikingly affordable prices.

The annual swarm is both a financial boon and a curse. The Britons here are not the hooligans who occasionally get blanket bans from foreign cities hosting U.K. soccer teams for fear of violent clashes. All of the fun in Magaluf gets posted to Instagram, which means it tends to be more photogenic than destructive.

But young British travelers are notorious for drinking a lot and spending little, and local reaction to the hard partying herd in Magaluf is split between come hithers (from hotel and bar owners) and go yons (from residents).

It’s a source of continuing tension, not just here but on other islands and in the country’s most beloved cities, including Barcelona and Madrid. Tourism accounts for more than 10 percent of Spain’s annual gross domestic product, the European Commission reports, and the United Kingdom provides the largest chunk of that windfall. More than 18 million British people visited Spain in 2019, about one-quarter of the total population, according to U.K. government statistics.

Spanish officials have already predicted that 2023 will break records.

“We don’t have factories here,” said Pepe Carbonell, an owner of Bondi Beach, a bar and restaurant in Magaluf. “We live off tourists, and the only bad customers are the ones who don’t come to Mallorca.”

Many tipple in moderation and spend plenty. But places like Magaluf are hotbeds of what is known here as the “tourism of excess.” The most notorious section of all is Punta Ballena, which has generated tales of hedonism for more than a generation.

Sexual assault is sadly common. There have also been fights and plenty of what is known as “balconying,” the practice of leaping from a balcony onto another balcony or into a swimming pool. (It’s popular enough that the U.K. Foreign, Commonwealth and Development Office published a warning against it.) Public nudity is so prevalent on this strip that signs here state, “Wear no clothes on the street, penalty 400 euros.”

“There are residents who live here, work here, take their kids to school here, and they have to see drunk people all the time, drugs, prostitution,” said Margalida Ramis, campaigner for GOB, a conservation nonprofit. “Living in this reality is like living in hell if you want a normal life.”

Typically, officials here broach the topic of low-end British tourism diplomatically, aware that tastes change and that if young people abandon places like Magaluf, the economic consequences will be severe. The future looks precarious. Like much of continental Europe, Spain has been sweltering in record heat this summer, and U.K. tabloids have suggested that tourists are choosing more temperate climates, even if they offer a fraction of the excitement.

“Costa Del Dull,” read a mid-August headline in The Daily Star, a London-based newspaper, riffing on the name of a southern coastal area of Spain, above a photograph of Hercule Poirot, the fictional Belgian detective. “Tourists swap traditional holiday favorites for boring Belgium to beat global warming crisis.”

Some Spanish politicians are too annoyed by the putative boorish behavior of the British tourists to exercise restraint.

“We have areas of our islands that are clearly marked by the tourism of excess,” Iago Negueruela, counselor of tourism of the Balearic government, which includes Mallorca, told elDiario.es, a Spanish digital newspaper. “That is what does not have to come back, and we will do everything possible so that it does not.”

Such sentiments led to a decree, passed by the regional government in January 2022, to curtail shenanigans in what were officially labeled red zones on three islands, including Mallorca. Party boats — a cruise with a D.J. for a fixed price and an open bar — were banned. So were bikini-clad women dancing in the windows of bars. Two-for-one drink specials were prohibited, too.

The goal was to increase the amount of luxury tourism, and some pricier hotels have popped up at safe distances from Punta Ballena. But if Magaluf is any indication, once a place is renowned for low-end getaways, the label is hard to shed. Plenty of vendors still cater to the bargain hunters. Mr. Henderson, for instance, bought a round-trip flight and three nights at a hotel for about $600, a price that included three meals, with three drinks at both lunch and dinner.

“And a shuttle to the airport is 10 pounds,” Mr. Henderson’s friend, Toby Euston, 18, said. “That’s why people come here. It’s cheap, and there’s nice weather.”

Deals on alcohol remain ubiquitous on the strip. On a recent Tuesday, around 1 a.m., the pavement was chockablock with tourists and what are known here as “reps.” These are bar employees whose job is to stand in the middle of the street and rope in passers-by.

It gives the place the feeling of a noisy, roiling bazaar where the only commodity for sale is liquor. A typical pitch: a triple shot and two more shots for seven euros. Every bar has a variation of this budget beverage offer. And music. A bunch of bars offer “silent disco,” where people listen and dance to music while wearing headphones.

The entire scene is familiar to Daniel Briggs, an ethnographer from Northumbria University in England, who spent four summers studying young British people in Magaluf for research underwritten by the Foreign Office, the arm of the U.K. government that safeguards citizens abroad. He saw plenty of fights and more than a few accidents that led to hospitalizations.

To him, the question of why British youngsters overindulge in Magaluf isn’t a mystery. They are generally taking their first vacation without parents, and that creates a sense that everyone is off the leash. And drinking has been central to British culture for centuries. Businesses here understand that, Professor Briggs said. Magaluf is carefully designed to exploit its core demographic.

“Bar owners know they’ve got a group of people who are young and ready to drink, and they’ve presented all sorts of options for them that encourages the worst behavior,” he said. “Obviously, this is a business.”

Many Britons here know that their reputation for unhinged behavior precedes them. Few seem to mind.

“I think British people don’t really care,” said Bella Fisher, a 21-year-old from Britain, who was walking near the beach with a friend. “They have, like, no standards. Like, they don’t really care about anything.”

But aren’t British people renowned for their reserve?

“Until you get to Magaluf,” she said.

In other countries, officials have explicitly tried to wave away British tourists. Amsterdam, for instance, started an online campaign in March that showed public-service ads to anyone searching the internet for terms like “pub crawl Amsterdam.”

“Coming to Amsterdam for a messy night?” read text in one video showing a man being arrested. “Stay away.”

In Spain, anger about the British is more likely to come from residents than government officials. There’s a derogatory word for visitors from Britain — guiri. It’s a shorthand for any British person behaving in what is regarded as a stereotypically British way — namely, drinking too much, fighting, ignoring social norms like stopping at traffic lights, and spending very little money.

Occasionally, the anger bubbles into something closer to rage. “Tourists go home,” someone spray painted not long ago on a hotel in Mallorca. In some cities, posters that ooze sarcasm have been put up that encourage balconying. One uses an image of a stick figure tripping off a balcony; underneath is text ticking through the benefits of this hazardous activity.

“Prevents gentrification,” the poster reads, “reduces the risk of heart disease, is LOTS of fun.”

Some club and bar owners in Magaluf detect an anti-British bias in laws designed to curtail the tourism of excess. Gerard Pietro, owner of Capitol Bar — which features a large pink neon sign that reads “Please don’t do coke in the bathroom” — says Magaluf should embrace its image and the people drawn to it.

“If I could get 50 customers a night who only bought Dom Pérignon, I’d be the happiest owner in the world, but that is not what happens here,” he said. “We have young people, and they have the right to party.”

During a recent daytime walk through the strip, Professor Briggs said the place looked pretty much the same as when he last spent a summer here, in 2019. He walked past a fish-and-chips spot called the Chippy, and pubs with distinctly British names, like the Red Lion. He stopped briefly at a bar, the Dirty Dog, after spotting a young man seated in a chair and apparently passed out on the patio. A couple of friends hovered nearby, not especially concerned.

“Is he all right?” asked Professor Briggs.

“He’s fine,” a friend said.

“How long you guys staying for?” Professor Briggs asked.

“Forever,” came the reply.

José Bautista contributed reporting.