During a trip to the Czech Republic this summer, Mr Bret Love desperately wanted to escape the crowds at Prague Castle, but could not. He was stuck in a Vltava River of humanity.
"There were thousands and thousands and thousands of people jostling for space," said the co-founder of Green Global Travel. "You start to feel like cattle being herded."
No matter what you call it - overtourism, overbooked or a foreign invasion - it is the same squeeze: A handful of destinations around the world are under siege by too many tourists. The stampede is having a deleterious effect on the culture, environment and spirit of these places.
Locals are getting pushed out. Foundations are crumbling. Tourists are complaining about other tourists.
"You try to keep these cities liveable for residents," said the Center for Responsible Travel's executive director Martha Honey, "but overtourism is killing these neighbourhoods and the reasons we go there."
Former Washington Post reporter Elizabeth Becker examined the consequences of rampant tourism in her expose, Overbooked: The Exploding Business Of Travel And Tourism.
The book's 2013 release coincided with a tourism milestone: For the first time, travellers had logged a billion international trips in one year.
The issue is not the industry itself, but the hordes of people who descend on one place during the same time period (often summer).
Destinations that are ill-equipped for the masses cannot keep up with the demand and everyone suffers for it. Ms Becker equates the situation to a dinner party host who plans for 12 guests and 12,000 hungry diners show up.
Travellers can help ease the pressure by tweaking their trips. For instance, visit off-season, book tickets to major attractions in advance and venture beyond the historical core.
Ms Becker also recommends longer holidays of two weeks over short getaways of two to five days. "You are planning your trip in a way that will be the least damaging. Your footprint is going to be less."
To further help beleaguered destinations, here are eight spots buckling under the weight of too many feet and alternatives that are similar in all but one category: They could use more - not fewer - tourists.
Venice Vs Verona
As if sinking were not enough, the Italian city of canals and masquerade balls is drowning in tourists.
More than 30 million people visit annually, swamping the local population of 50,000 and causing rifts between the two camps.
Several years ago, Unesco warned Venetian officials that the city could end up on its endangered list of heritage sites if they did not curb their enthusiasm for tourists.
Officials responded with a raft of initiatives, such as relocating the cruise ship port to the mainland and banning new hotels in the historical city centre.
To visit or not to visit, that is such a silly question. Of course you should.
The Italian city 120km west of Venice is the setting of two Shakespeare plays. Bard fans can practise their lines beneath Juliet's balcony while relationship-seekers can give her statue a hopeful tap instead of swiping right.
The Unesco World Heritage site comes with the requisite old-world charms, such as a piazza populated by statues of Greek gods, a performing arts venue inhabiting a Roman amphitheatre and a 13th-century castle built to defend the Veronese from invaders.
The destination is also known for its European Union-protected variety of rice, a mainstay on local menus. Follow the grain along La Strada del Riso Vialone Nano Veronese IGP - longhand for the Rice Route.
For a wilder ride than a gondola, go rafting down the Adige River. Ask nicely and maybe your guide will sing O Sole Mio.
Barcelona Vs Seville
The capital of Catalonia is the most-visited city in Spain, drawing 32 million people, more than 30 times its population.
In one municipal survey, residents blasted tourism as the second-worst urban ill after unemployment. Anti-tourist graffiti has started popping up and locals have protested against the loss of their home to foreign invaders.
In addition to land travellers, nearly three million passengers arrive by cruise ship annually, a surge officials hope to stem by relocating the port outside the city centre by 2025.
The current mayor, Ms Ada Colau, won the election on her proposals to control unchecked tourism. Measures include fining Airbnb.com for renting unlicensed properties, raising the parking rate for coach buses idling at popular tourist spots and slowing the proliferation of hotel rooms, including banning new properties in the city's congested hub.
The city is the cultural and business centre of the Andalusian region and a great place to take flamenco for a spin.
The world's largest Gothic church, the Seville Cathedral, brings guests closer to the heavens on a rooftop walk.
Seville boasts its own regional style that blends Islamic and Christian aesthetics. Play I-Spy Mudejar around town: Look for vibrant glazed tiles with nature themes, rounded arches and carved wood ceilings.
If you are pressed for time, go straight to the Royal Alcazar, a palace complex with a strong Mudejar streak.
Moorish influences - chickpeas, cumin, aubergine - appear in the tapas too. Of course, the primo ingredient is jamon Iberico.
Vegetarians who would rather meet the acorn-snuffling pigs than consume them can take a farm tour in the countryside. Or eat a Seville orange.
Dubrovnik Vs Rovinj
The TV series Game Of Thrones has been a boon for HBO and fantasy-fiction fans, but a burden for the Croatian city. The Pearl of the Adriatic has been squirming beneath the crush of cruisers when the sword-wielding tourists showed up, searching for the real-life Westeros.
The onslaught has even troubled Unesco - the United Nations Educational, Scientific and Cultural Organisation - which had designated the Old City a World Heritage site in 1979. It recommended limiting the number of visitors to 8,000 people a day; the newly elected mayor, Mr Mato Frankovic, countered with a lower figure of 4,000.
He has also promised to tackle the cruise-ship jam.
During the high season, three to four ships often sail into port daily. As a remedy, he proposed curbing the number of cruises during peak times and staggering arrivals. The plan could alleviate pressure on key attractions such as the Stradun, a pedestrian promenade, and the mediaeval walls, which bore the weight of more than 10,000 people on one day in August 2016.
The Croatian fishing port shares the same coast as Dubrovnik and draws tourists and cruise ships during the summer, but not nearly as many as its southern neighbour. Typically, three or four ships tender a month - not day - during the summer.
The town sits on the Istrian Peninsula in the Adriatic and was an island before the Venetians filled in the channel in 1763.
The Italians, who twice controlled the city, have left their prints all over the place.
You can see their influence on the Church of St Euphemia, as well as in the many restaurants serving pastas and pizza laced with truffles foraged from the nearby Motovun Forest.
To visit the archipelago islands or the Istrian port town of Porec, catch a water taxi or ferry.
Reykjavik Vs Baffin Island
Go ahead and wag a finger at Icelandair.
The budget airline popularised the practice of adding a free stopover in Iceland en route to continental Europe. More recently, Wow Air, which started service in 2011, extended the perk to its passengers. The number of international air travellers has skyrocketed; visits between 2016 and last year grew 25 per cent, to 2.2 million.
The Icelandic population is 350,000.
Most tourists congregate in Reykjavik and the south-west region, clogging the capital and the Golden Circle, the driving loop fizzing with geothermal features.
The deluge has caused a shortage of hotel rooms. Airbnb has helped fill the vacuum, but the shift to short-term rentals has stressed the limited supply of units and caused rents to spike.
To mitigate the housing crunch, the government has placed restrictions on Airbnb property owners.
OVERLOOKED: BAFFIN ISLAND
Baffin Island, in the way-north Canadian territory of Nunavut, is the fifth-largest isle in the world, a baker's dozen spots ahead of Iceland.
The landmass in the North Atlantic Ocean shares several characteristics with the Scandinavian country, such as fjords, the midnight sun, the Northern lights, the Arctic Circle and, according to recent archaeology digs, Vikings.
Though the Nunavut capital of Iqaluit is minuscule compared with Reykjavik, visitors can soak up the northern culture at the Nunatta Sunakkutaangit Museum, which specialises in Inuit art and artefacts; and during the Toonik Tyme Festival, a spring-time celebration of tribal traditions, including igloo-building, dog sledding and skijoring - where a person on skis is pulled by a horse, dogs or a motor vehicle.
At Auyuittuq National Park, you can ski, hike on glaciers and ice fields, and climb Mount Thor, which has the world's longest vertical drop. For less chilling activities (adrenaline-wise), scour Sirmilik National Park for wildlife such as narwhals, caribou and ringed seals.
Machu Picchu Vs Choquequirao
OVERBOOKED: MACHU PICCHU
The 15th-century Incan site has survived the Spanish conquest, a scandal involving a Yale explorer and flooding, but its downfall could be tourists.
In 2013, Unesco aired its concerns about the degradation of Peru's top attraction. Among its myriad offences: "Impacts of tourism/visitor/recreation."
In response, the government and Unesco capped the number of daily visitors at 2,500.
However, last year, 1.4 million people toured the ruins, a clear breach of the directive.
To control the chaos, the government announced new restrictions last July, such as requiring accredited guides to accompany all visitors (no more independent wandering) and funnelling hikers onto three established routes.
Also gone: staying all day. You can buy a ticket for the morning or afternoon slot, but once your time is up, your visit is over.
Machu Picchu and Choquequirao might as well be twins: Both ancient Incan cities are in Peru's Andes Mountains and demonstrate the same architectural style and building techniques.
They also have the same jumping-off point (the city of Cusco) and are accessible by multi-day trek, though the Choquequirao Hike is more arduous than the Inca Trail.
Despite the similarities, Choquequirao, which is three times larger than Machu Picchu, receives a tiny fraction of visitors - a dozen to 30 adventurers a day.
Why the trickle? Maybe because the site is less-known. Archaeologists did not start excavating the ruins until the 1970s, more than a half-century after Machu Picchu was cleared.
Or it is less-developed: Only one-third of the site has been exposed.
Mount Everest Vs Mount Toubkal
OVERBOOKED: MOUNT EVEREST
The world's tallest mountain, which straddles Nepal and Tibet, suffers from some of the same ills as urban centres: trash and traffic.
To reach the summit at 8,848m, trekkers sometimes have to wait in lines as long as those for Disney World's Space Mountain.
Litter, including empty oxygen tanks, clutters the trail.
The crowds are endangering the environment as well as themselves. In 2014 and 2015, deadly avalanches took the lives of 16 Sherpas and 19 climbers respectively.
And yet the trekkers still come, including novices with little experience in high-altitude adventures.
Last year, the government issued a record number of climbing permits, nearly 375 permission slips for 43 international expedition teams. That figure does not include the porters and guides, who more than double the number.
OVERLOOKED: MOUNT TOUBKAL
The tallest peak in Morocco's Atlas mountains is a mouse compared with Asia's lions, but it does dwarf most of the major mountains in the Americas, Europe and Oceana. Plus, it comes with a bonus bragging right: You can tell your ground-level friends that you have climbed the highest point in North Africa.
Mr Lee Thompson, co-founder of Flash Pack, a London-based tour company, says Toubkal is as mentally challenging as the ascent to the Everest base camp, but is more accessible to hikers with less experience and more moderate fitness levels.
The more than 4,160m-tall mountain sits within Toubkal National Park, about 65km south of Marrakesh. The climb takes about two days and halfway up the mountain, you can load up on carbs and mint tea in Sidi Chamharouch, a Berber settlement with a Muslim shrine.
On summit day, you will wake with the roosters and trek 10 hours to reach your crowning achievement. You have earned that hammam.
Amsterdam Vs Ljubljana
Tourists outnumber residents by double-digit millions, so it is no wonder the high of tourism has worn off.
To reclaim the Dutch capital, officials are mulling or have executed several laws, such as doubling the tax on hotel rooms and banning short-term Airbnb rentals and souvenir shops in the historical centre.
They are also considering relocating the cruise-ship berth and passenger terminal away from the middle of the action, a move that will affect cruisers on more than 2,000 ocean liners and riverboats.
In the red-light district, law enforcement officers have started ticketing bad behaviour such as public drinking and littering. A new colour-coded system will monitor crowds - a red signal could result in street closures, for example.
To lure visitors out of the choked centre, the tourism organisation responsible for the City Card expanded benefits to include day trips outside the city, such as to Haarlem, Zaanse Schans and Keukenhof, where you can tiptoe through the tulip fields.
Tulips, bikes and waterways define Amsterdam, but the trio also describe Ljubljana.
The capital of Slovenia shares many of the same attributes as its western neighbour, such as the Volcji Potok Arboretum, which holds a tulip exhibit every April; a bike-share programme with rentals and more than 5,450 cycling routes; and the Ljubljana River, which wriggles through marshes and the heart of the city.
The European Commission crowned the city the European Green Capital in 2016.
You can inhale the fresh air aboard Kavalirs (Gentle Helpers), the free public transport system that runs on electricity; and in Tivoli Garden, the city's largest park.
The Central Market is a feeding frenzy with an open-air and covered market, plus food shops and other retail.
At the Open Market, which runs from April through October, more than 30 chefs prepare local and international dishes.
Rome Vs Turin
In Euromonitor International's 2017 list of the top 100 cities, the marketing research firm expects visitation numbers for Rome to surpass 10 million by 2020, but you do not have to wait for the future to see the toll tourism has taken on the Eternal City.
In 2015, the Spanish Steps closed for a year to reverse damage caused by too many people. The renovation, which cost US$1.7 million, removed stains, repaired broken pacing stones and relevelled the steps. The lines to enter the city's Roman ruins and museums are notorious.
Like Rome, the ghosts of Roman civilisation haunt this Piemonte city in northern Italy.
You can find them under your feet, on the cobblestone streets and, looming overhead, in the 16-sided towers bookending the Palatine Gate. Quadrilatero Romano, or the Roman Quarter, showcases the period's signature grid as well as ancient wall ruins and the excavated remains of a Roman theatre.
The Royal Museums contain several institutions that track the city's arc from Roman times to Italian unification in the 1800s. (Turin was the first capital of Uno Italy.)
Among the complex's cultural attractions: the Archaeological Museum; the Royal Garden, Armoury and Library; and the Chapel of the Holy Shroud, which reopened in September after a 28-year closure.
Rome might be la dolce vita of Vespas, but Turin is the headquarters of dashing rides such as Fiat and Alfa Romeo. The National Automobile Museum has amassed a collection of more than 200 vehicles from France, Britain, Germany, Poland, the Netherlands, Spain, the United States and, of course, Italy.