Nudism is nothing new. Neither, of course, is travel. But tourists getting their kit off and snapping photos at famed attractions? This appears to have become a 'thing'.
Last week, three tourists were issued a warning at Machu Picchu's Incan citadel for baring their buttocks in aid of a holiday snap. It's against the rules you see, on account of locals finding it disrespectful, but it happens so often that in 2014, the Peruvian culture ministry felt inclined to issue a reminder that all nudity at the Unesco World Heritage Site is banned.
The three in question were all mid-twenties travellers, one French, one from the Netherlands and one Swiss. The latter, who wished to remain anonymous, later told newspaper 20 Minuten that wardens on the site had informed his group "incidents like this happened regularly" but admitted: "it was a dumb idea". (He got off lucky. A British tourist was arrested for the same crime at Machu Picchu and charged with moral misconduct in 2016.)
Earlier this month, a female tourist in Thailand was photographed gyrating naked against the Hin Ta rock in Koh Samui - a land feature phallic in shape and considered sacred by locals.
Thai police described the incident as "not acceptable", and a manhunt is currently underway for the perpetrator. They had a similar task on their hands in February when a model stripped at the 12-ft tall Hin Ta, and yet another in August of 2016.
We're not done yet. In 2015, three French men were fined and deported from Cambodia for getting naked at Angkor Wat. In 2010, an exotic dancer filmed herself writhing around atop Australia's Uluru rock in an act that made headlines for all the wrong reasons - depending on who you ask.
"I could feel the good energy of the place and I just needed to express myself," she told Channel Seven.
That's probably enough of the case history. Onto more pressing matters.
Why are people doing this?
Attention, for starters, and notoriety. Tourists posing naked translates to surefire social media interest. Facebook page Naked At Monuments - whose "about" section reads: "We get naked around the world, pretty self explanatory really" - has more than 7,500 followers and has sparked media coverage a number of times in the past.
Instagram has more than its fair share of accounts devoted to clothes-off tourism - either lone travellers (ionlytravel, followers: 54.6k, tagline: "my goal is to visit every country in the world and get nude") or those which share submissions from others (getnakedworldwide, followers: 84.3k, tagline: "travel the world, get in your birthday suit and [send us] the photo - more bums the more likely to be featured!")
Etiquette expert William Hanson is not impressed. "Taking your clothes off at notable landmarks is the height of narcissism," he tells us. "Sadly, it's not unexpected in the 'look at me' era of today."
The founder of Naked At Monuments was fairly nonchalant about the whole business.
"I started doing it as a joke between my friends as a way to take traditional travel photos and turn them on their head," he explains.
"The website was actually started as a way for me to get my travel writing out, but in the end other writing jobs got in the way and that kind of fell by the wayside. Though there still seemed to be a massive interest in the photos, and people from all over the world started sending them in."
Psychologist and pop culture analyst Emma Kenny told us: "Nakedness provokes attention, and in a day and age where travel bloggers are ten a penny, the need for reinvention and remaining relevant is more pressured than ever. This combined with the permission base that exists all over social media involving famous naked celebrities encourages the stretching of personal boundaries."
Psychologist Dr Arthur Cassidy, who specialises in celebrities and social media, has sterner words: "Individuals who engage in this high risk social behaviour frequently lack empathy, show core traits of being impulsive, happy-go-lucky, non-conforming and revel in disobeying sociocultural rules of the host country."
But wait, there's an important distinction to be made before anyone gets into too much of a flap.
See also: Naked tourists blamed for earthquake
Naked tourists vs. nudists
If you've ever studied the subject of art history, you'll likely have been lectured on the profound difference between the terms "naked" and "nude" - the former evoking a sense of exposure, a state of undress; and the latter more concerning a celebration of the human form.
Similarly, there's a big difference between stripping at a public monument for cheap thrills on a packed beach in Thailand, and posing nude in a secluded meadow of wild flowers in the far reaches of Croatia.
Media psychologist Dr Pamela Rutledge, weighs in: "The travellers snapping naked photos at public monuments are indulging in risky behaviour without regard to the local culture."
It's a "selfish" activity she maintains, comparing it to the craze of scoring selfies with exploited wild animals, or performing dangerous stunts at tourist destinations to garner attention. "The entertainment value is amplified in a group, where people are inclined to do slightly riskier things," she adds.
On the other hand, "Nudist travellers", Dr Rutledge says, tend to care more about spreading messages of body positivity and are careful to seek out "nudist-appropriate" locations.
Stella Cordes, the Dutch photographer and travel blogger behind A Naked Girl, who has amassed 195k followers on Instagram for her nude shots, takes this distinction very seriously.
"You won't see me go naked public places," she tells us. "Especially with children around. I do wish being nude was more acceptable as there is nothing wrong with it, but for now I take my stand."
On Instagram's policy, which prohibits photos that show full-frontal nudity (bum cheeks are OK), she has no quibbles. "I think it's fair and we should play by the rules."
Do we all need to be less prudish?
If you were to spot a fellow traveller shedding their clothes and posing next to the Eiffel Tower, would you point and giggle, quietly judge them and shuffle on, or gasp and report it to the nearest authorities forthwith? That depends entirely on your nature, of course.
Travellers who love nothing more than to bare all in the wilderness and share their posteriors with their army of social media followers are surely no cause for alarm. Naked tourist snaps taken around attractions that hold a sacred significance for locals seems to be a good place to draw the line.
The Naked at Monuments founder we heard from earlier has this: "Use your common sense. If you're going to a deeply religious site or a place where locals would be offended by your nudity, then it's probably not the right idea.
"But provided you're in the right circumstances I think it's harmless. People who get up-in-arms about it would be better served protesting something like sex tourism or what travel has done to the environment."
The Telegraph, London