Vanuatu Post is a one-of-a-kind post office. Located about 160 feet off the coast of Vanuatu, sits the world's first underwater post office. The uber-cool post office was started back in 2003 and allows tourists to send postcards back home from under the sea. Interestingly, the postcards are made of waterproof plastic and embossed with a special stamp. The staff comprises special dive masters to make the deliveries and visitors know that the post office is open for business when a flag is flown at the surface.