Floreana, an island in the Galápagos, is known as the place where Charles Darwin researched natural selection.
But that’s not its only claim to fame.
The remote site off Ecuador’s coast — one of the world’s most ecologically diverse and uninhabitable places — also operates a unique, stampless system of sending mail.
In 1793, traveling whalers anchored at Floreana Island created a way to send news to loved ones back home, National Geographic recently reported.
Wandering fishermen placed addressed letters in a wooden barrel for seamen on other passing ships to collect, stamp and deliver if the boats sailed toward the notes’ destination.
Explorers documented the unconventional practice during the 19th century, with the box becoming more and more covered in keepsakes as travelers passed through.
“Post Office Bay” continues today, where visitors pick up letters destined to homes near them and drop off postcards of their own.
Tourists hand deliver or mail the letters they collect, although National Geographic notes island guides are known to say “slapping a stamp on a letter and dropping it in a mailbox is cheating.”