A Postal Service Beneath the Ocean
Japan’s Susami Bay is home to one of the world’s most fascinating attractions, an underwater mailbox placed 10 meters below sea level, transforming a traditional postal service into a memorable underwater experience for divers.
Where Susami Bay Is Located
Susami Bay lies along the coast of Wakayama Prefecture in southern Japan, a region known for clear waters, rich marine biodiversity, and strong diving tourism appeal.
Origins of the Underwater Mailbox
The underwater mailbox was initially installed as a creative tourism experiment, but its popularity quickly turned it into a functioning and officially recognized postal attraction.
Why the Mailbox Is Placed at 10 Meters Depth
The 10-meter depth was carefully chosen to ensure safety and accessibility for beginner-level scuba divers while still offering a genuine underwater experience.
How Divers Write Letters Underwater
Visitors use waterproof postcards and oil-based pens that allow writing underwater without ink dissolving or paper damage.
The Process of Posting a Letter Under the Sea
Divers simply place their completed postcards into the submerged mailbox, after which staff retrieve the letters and process them on land.
Official Recognition by Japan Post
Japan Post officially recognizes the underwater mailbox, and every letter receives a special Susami Bay postmark, making it a unique collectible.
Annual Volume of Letters Received
The underwater mailbox receives approximately 1,000 to 1,500 letters each year, sent by divers from Japan and around the world.
Who Uses the Underwater Post Office
Most letters are sent by recreational divers, tourists, and underwater photography enthusiasts seeking a once-in-a-lifetime experience.
Tourism Impact on Susami Bay
The attraction significantly boosted local tourism, benefiting dive shops, instructors, and nearby businesses.
A Unique Blend of Adventure and Communication
Posting a letter underwater combines physical adventure with emotional storytelling, making each message deeply personal and memorable.
Marine Life Surrounding the Mailbox
Fish and corals often surround the mailbox, adding to the visual appeal and enhancing the overall diving experience.
Environmental Protection Measures
The mailbox is built using corrosion-resistant and eco-safe materials to ensure no harm to marine ecosystems.
Why Japan Embraces Creative Attractions
Japan is known for blending tradition with innovation, and the underwater mailbox reflects this cultural creativity perfectly.
Global Attention and Viral Popularity
Photos and videos of divers mailing letters underwater frequently go viral, attracting international visitors to Susami Bay.
Educational Value for Visitors
The attraction encourages respect for marine life and responsible diving while demonstrating how everyday systems can adapt creatively.
Why the Underwater Mailbox Still Thrives
Its simplicity, authenticity, and official status keep interest alive year after year.
Conclusion
Japan’s Susami Bay underwater mailbox proves that even traditional services can be reimagined, delivering messages and memories from 10 meters below the sea.