Susami, is a fishing town in Wakayama Perfecture, Japan with a population of around 5,000 people. A a Guinness World Record Holder since 2002 , this deepest underwater postbox is located at a depth of 10 meters off its coast.
The post box was established in the year 1999 to promote the country’s ancient Kumano Kodo pilgrimage trail and the surrounding areas in the southern part of Wakayama’s Kii Peninsula.
The mailbox receives around 1,000 to 1,500 pieces of mails annually, which are collected by the employee of the Yamatani Dive Shop. It’s the same shop from where people buy water-resistant postcards and write messages with an oil- based paint marker.
Since the seawater severely corrodes the iron box, two of them are used on alternate basis after every six months so that the one can be cleaned and repainted at the time of the other.
The items in the box are delivered to the recipients within a week of being posted.