If exploring sunken wrecks sounds fun, then you are in luck because Greece is home to one of the most famous wrecks in the world. The HMHS Britannic was a WWI hospital ship that sank off the coast of the little island of Kea, also called Tzia, in 1916. A word of caution is needed as the depth and complexity of the wreck makes it a difficult dive for beginners and should only be explored by advanced divers.