First, it was a spate of tourists getting busted for getting naked and posing for photos at Machu Picchu.
Now, three women are behind a growing Internet craze to get people to take topless vacation photos.
Brits Olivia Edginton, 20, Lydia Buckler, 21, and Norwegian Ingvild Marstein Olsen, 20., are encouraging people around the world to strip to the waist with their Topless Tour project, reports the U.K.'s Orange News.
People around the world are following their lead and posting photos of themselves from behind as they expose their naked chests --be it in crowed cities or on remote mountaintops.
The Topless Tour currently has over 9000 followers on Instagram, and their Facebook page has received thousands of likes and hundreds of picture submissions from 28 countries. Travelers spread the word by tagging their photos with #TheToplessTour.
The images show only the backs of the subjects --but isn't relegated to photos of just women.
The creators said their project wasn't started to be controversial.
According to Edginton, the photos are symbolic and about opening your heart to the world.
"The Topless Tour is the opening of your bare chest and heart to the world. Everyone is very proud of the message, our parents think it's really refreshing for young women to be embracing who they are and love for their body," she said.
So far, they haven't gotten into any trouble with the authorities - yet.
The women, who are roommates and dance students at Greenwich’s Trinity Laban Conservatoire of Music and Dance, have so far posed topless in Oslo, New York, Manchester, Berlin and London.
The Topless Tour started in 2012 while the girls visited Olsen's hometown of Brumunddal and went for a walk around nearby Lake Mjosa.