Mail a postcard under the sea from the world’s deepest mailbox!

Venture inside…to discover new worlds!

Undersea Mailbox

Video courtesy of Club Noah Susami
Imagine this: you’re swimming in the warm waters of beautiful southern Wakayama, and you want to tell that special someone how it feels… In Susami, at the southern end of the Kii Peninsula, you can do just that! Write your message in permanent marker on a special waterproof postcard and dive off Susami’s beach to Japan’s one and only undersea mailbox! Of course, you can send it to yourself, too. It’s sure to make the memory last a lifetime.

A mailbox worthy of the Guinness Book

Susami’s undersea mailbox was installed in 1999 by the executive committee of the Susami Marine Sports Festival, part of the Nanki Kumano Experiential Expo. It’s listed in the Guinness Book of World Records as the “world’s deepest mailbox.” The postcards collected from the box are sent through the Susami post office to destinations all over Japan and the world. You don’t need to be a licensed diver; guided dives are available for anyone who wants to use the box. There’s no other experience quite like it!

The undersea fun continues with a hula hoop diving course!

On the sea floor near the mailbox, you’ll find hula hoops set up in a course for divers to swim through. This is your chance to show off your underwater moves as you deftly maneuver through the hoops. Channel your inner dolphin (or mermaid) and give it a try!

Adventure World

There’s no question who the stars are in Adventure World, just up the coast from Susami in Shirahama: the pandas! Get up close with a family of five giant pandas and many other animals in this fun-filled theme park.

Dine on the elusive kue fish

The deep-sea kue is known as the “phantom fish” due to how hard it is to catch. Thanks to a successful aquaculture effort at Kinki University, it’s now a local Shirahama delicacy. Its high collagen content gives it a marvelous flavor!


Location/Access Susami, Susami-cho, Nishimuro-gun, Wakayama
About 12m by bus or taxi from Nanki-Shirahama Airport to JR Shirahama Station → about 20minutes by train from JR Shirahama Station to JR Susami Station
Inquiries Club Noah Susami (Undersea Mailbox)
TEL 0739-55-4511

Shirahama Tourism Association
TEL 0739-43-5511

Adventure World
TEL 0570-06-4481

The posted contents are current as of the day when posted, but may have changed since posting.

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