On August 16, 1939, the world’s first undersea post office opened in the Bahamas.  It was developed by an undersea photographer and garnered significant interest from around the world.  Decades later, more underwater post offices and post boxes were established in other countries, many of which are still in operation today.

The first undersea post office was made possible by photographer John Ernest Williamson, a pioneer in undersea photography.  His father had created tube that enabled communication and air flow to underwater depths of more than 200 feet.  Williamson expanded on the idea and designed a chamber with a glass window that could be attached to the tube and lowered to the sea floor.  Williamson would lower himself in the tube to take photographs of the sea floor and its inhabitants.  He called it the Williamson Photosphere and he set it up in the Bahamas in 1914.  The Bahamas had clear waters that let the sun reach down to the seafloor to help illuminate his images.

In 1939, he started the Bahamas-Williamson Undersea Expedition to film underwater scenes.  It was a scientific expedition that drew increasing interest, leading organizers to decide to set up a post office there for publicity.  The post office opened on August 16, 1939.

The first two letters sent from the post office were written by the governor of the Bahamas.  He took the tube down to the underwater post office and sent letters to King George VI and President Franklin Roosevelt.  Roosevelt sent a response that read: “I greatly appreciate your kind thought in writing to me upon the occasion of the opening of this most unusual and interesting post office.  I am sure that this unique contribution to science will give immeasurable pleasure to those persons who are privileged to visit the Bahamas.”  Those who could make the trip flocked to the unique post office and collectors around the world ordered covers bearing the special “Sea Floor” postmark.  The post office closed in 1941.  You can view a cover sent from the post office here, which includes a cachet depicting it.

The small fishing town of Susami Bay, Japan, established an underwater postbox in 1999 during a fair to bring attention to the area.  It once held the record for the deepest underwater postbox at 10 meters (about 32 feet).  The box receives up to 1,500 pieces of mail per year.  Mailers use special waterproof cards and write their messages with oil-based paint markers.  Today, some of the cards are edible and flavored.  Every six months, the mailbox is repainted, and every year, it is replaced with an old, unused mailbox. Click here for a brief video about the Susami mailbox.

Vanuatu opened its own underwater post office in May 2003.  About 160 feet off the coast and 10 feet below the surface, the post office is made from a converted fiberglass water tank.  Next to it stands a mailbox that vacationers can swim up to and mail out their postcards.  They must use special postcards, made of waterproof plastic and embossed with a special stamp.  The post office has a special metal device to cancel the postcards without ink, since it would smear.  A flag flies at the surface so they know the post office is open.  When it first opened, the post office trained postal clerks to scuba dive to run the undersea post.  However, because diving requires specialized training, local dive masters often help.  Click here for a photo of the Vanuatu post office.

Opened in 2004, Risor, Norway’s post office differs from the others in that it the only dry underwater post office.  The post office itself is an old diving bell 4 meters (about 13 feet) below sea-level.  Mailers place their letters in a postbox on the nearby pier.  The letters are placed in a watertight bag and taken down to the post office.  Inside the dry bell, the letters are stamped and brought back to the surface to be transported.  Click here for a photo of the Norway post office.

In 2015, Pulau Layang-Layang, Malaysia, took the record for the deepest underwater post box – at 40 meters (about 131 feet) below sea level.  Postcards placed in the mailbox are sealed in waterproof bags and then given a special postmark and stamped with the Malaysia Book of Records logo.  Click here for a photo of the Malaysia post box.