It is not the sheer number of tourists descending on Venice that bothers Italian food blogger Monica Cesarato so much as the type of visitor.
Not so long ago Venice was considered the trip of a lifetime, said Cesarato, who runs gastronomic tours there. Visitors took days, even weeks, to explore the City of Canals, spending money in local restaurants and businesses.
Today they pile off cruise ships and coaches, go on whirlwind tours run by non-locals, take umpteen selfies and buy little more than a cheap trinket made in China.
As millions of holidaymakers head off for their summer break, increasing numbers of popular destinations are saying they cannot take much more.
The Belgian city of Bruges is cracking down on cruise ships, Paris wants to limit coaches, Prague is fed up with beer bikes — and one Thai beach has banned tourists altogether.
While tourism creates jobs and wealth, there is growing awareness of its negative impacts, from environmental damage to the destruction of neighborhoods as residents are priced out.
The problems have created a backlash, spawning anti-tourism movements and protests from Amsterdam to Rome and Dubrovnik, the Croatian city featured in the TV show "Game of Thrones."
Mass tourism took off after World War II. Last year there were 1.4 billion tourist arrivals, up from 25 million in 1950, according to the United Nations World Tourism Organization, with Europe absorbing half of them.
The nation generating the most tourists is China — 143 million trips abroad in 2017 — while France and Spain receive the most visits — more than 80 million a year.
The boom is down to a fast-expanding global middle class combined with a proliferation of budget airlines and online travel agents which have made travel cheap and easy. A Londoner can fly to the south of France for less than 20 pounds ($25).
"The perception of going on holiday has shifted from being pretty much a privilege to becoming very much a right," said Marina Novelli, professor of tourism and international development at the University of Brighton.
She said for decades tourism authorities and ministries have only measured success in terms of increased visitor numbers.
"This model no longer works and that's probably the most important message to get out there," she said, warning that overcrowding and "Disneyfication" in some places could destroy the charms that draw tourists in the first place.
"If we look at numbers only, and we don't look in more detail at the impact — economic, social, environmental — we risk killing the goose that lays the golden egg."
Nowhere epitomizes the problems as much as Venice, which attracts 30 million tourists a year to its magnificent canals and bridges.
As visitor numbers soar, the "Queen of the Adriatic" has seen its own population plummet from about 175,000 after World War II to just over 50,000.
"We used to have a low season when Venetians had time to recuperate. Now it's all year round and Venetians don't get the city for themselves anymore," Cesarato told the Thomson Reuters Foundation.
Stores like bakeries and greengrocers and community services are vanishing as residents bail out. "I can only just see this getting worse and worse," she added.
UNESCO has threatened to add Venice to its list of endangered heritage sites, partly because of problems with tourism.
Calls to ban cruise ships from the center of Venice intensified this summer after one hulking liner crashed and a second had a narrow miss.
Travel experts say cruise ships — along with other day-trippers — exacerbate "overtourism" because passengers increase congestion while spending little locally.
Several European destinations including Dubrovnik, Bruges and the Greek island of Santorini, have slapped restrictions on cruise ships. Barcelona's mayor has also promised action.
Another phenomenon fueling anti-tourism protests is the rise of short-stay letting platforms such as Airbnb, which are blamed for hiking rents and changing neighborhoods.
With landlords able to make far more on holiday lets than traditional leases, housing supply has shrunk and residents have been squeezed out.
Paris has about 60,000 homes listed on Airbnb, Amsterdam 19,600, Barcelona 18,300 and Venice 8,500, according to Inside Airbnb, a website highlighting the company's impact on neighborhoods.
Cities including Palma de Mallorca, Paris, Amsterdam and London have introduced or are discussing measures to mitigate the impact.
While overtourism is most apparent in Europe's historic cities, the World Travel & Tourism Council (WTTC) warned last month that certain cities in Asia, Latin America and Africa could be at risk if they do not plan ahead.
Nor are problems confined to cities. Thailand closed a beach made famous by the Leonardo DiCaprio movie "The Beach" indefinitely last year to give its ecosystem time to recover.
The Philippines' top holiday island of Boracay also shut for a clean-up last year after the president raged it had become a "cesspool" and warned of an environmental disaster.
The Indonesian island of Bali and Italian island of Capri both banned single-use plastics this year, the latter threatening hefty fines for violations.
Rochelle Turner, research director at the WTTC, which represents the travel and tourism private sector, said there was a need for more lateral thinking to disperse tourists away from congested spots.
She cited an innovative example of a travel company that took Asian tourists to an English farm when the canola fields were ablaze with yellow flowers, creating dramatic vistas.
Turner said Belgium was among countries making major efforts to diversify tourism.
It is moving away from marketing its medieval cities like Bruges and Ghent as it tries to lure cyclists, art lovers and beer aficionados to its country lanes, cultural gems and monastery breweries — taking them off well-worn tourist trails.
But Turner said the debate around overtourism often ignored the many benefits the industry brought, including the protection of lands and wildlife and the preservation of buildings that might otherwise decay for lack of money.
"Yes, we hold our hands up — things have got a little out of control in some places — but tourism is not a bad news story. It brings tremendous good," she added.