Built in 1999, the mailbox in Susami (Japan) once received the Guinness World Record as the world’s deepest mailbox, 10 meters below sea level.
Mr. Matsumoto, who runs the post office in the town of Susami, had the idea to build a mailbox on the sea floor to promote tourism in his area. Up to now, about 38,000 postcards have been sent to this special mailbox. And of course, to send it in a special way, you need a waterproof paper and an ink pen made from oil. Strangely enough, Susami has become a place to attract many tourists, and is an ideal place for divers who want to explore this interesting mailbox.