Unusual Post Boxes in the World

World’s Deepest Underwater Post Box (33 feet-10 meters below Sea Level)
Susami, Japan

The mailbox was installed in 1999 as a part of a marine sports festival event & can be used to send mail. Divers can post a waterproof plastic postcard into the box & a local diving shop staff member picks up cards once a day as part of regular mail service.