1. Hideaway Island, Vanuatu
Situated within a marine sanctuary off Hideaway Island, this underwater post office even has its own Tripadvisor entry (it's got a 4 star average, in case you're wondering). The post office is open to visiting snorkellers as well as guests, and local postal workers are on hand to help if you can't duckdive the three metres to post your letter.
2. Paradise Island, Bahamas
The Bahamas can claim to be the birthplace of 'wet' mail: in 1939, a photosphere used for filming a silent version of Jules Verne‘s 20,000 Leagues Under the Sea was converted into an underwater post office and renamed 'Sea Floor Bahamas'. Adjacent to a spiralling 100-foot tower, the post box was recently commemorated with a set of its very own stamps.
3. St Thomas, US Virgin Islands
Located inside the Coral World Marine Park’s Underwater Observatory, this is one of a handful of underwater postboxes in the world where you won't get wet posting your letter. More importantly, it won't get wet either.
4. Risør, Norway
The world's first 'dry' underwater post office, the Risør Underwater Post Office in southern Norway came close to being shut down in 2011, when very few letters were being sent using it. The local tourism board and local businesses sprang into action and offered their support, so it's still open today.
5. Jemeluk Beach, Bali
Part of the Jemeluk Bay Underwater Gallery, this post box sits amongst a collection of underwater art including a mermaid (sponsored by Bodyshop) and a huge baby's head. The area has been declared a 'no fishing' zone, so you know your mail is safe.
6. Mataking Island, Malaysia
When the local Reef Dive Resort on Mataking Island in Sabah sank a cargo ship to create an artificial reef for divers, they had the foresight to fit an underwater mailbox, the first of its kind in Malaysia. Divers seal their mail inside a plastic bag and get it postmarked with a special stamp before their dive. A local postal worker collects the mail every two weeks.
7. Susami Bay, Japan
Recognised as the world's deepest underwater postbox by the Guinness Book of World Records in 2002, this functioning mailbox sits 33 feet under the sea in Susami Bay in Japan's Wakayama prefecture. Divers are encourage to buy water-resistant postcards from the local general store and use a supplied oil-based marker to write on them. The cards are collected every few days and taken to the local post office – even the edible, squid-flavoured ones, developed by a local entrepreneur.
