Ancient shipwrecks, sunken World War II vessels, underwater caves, and submerged cities - these are but a few of the treasures classified as significant and in need of protection on UNESCO's underwater cultural heritage list.

UNESCO has been promoting the protection of the world's cultural and natural heritage for almost four decades, yet its convention on underwater cultural heritage has been in existence only since 2001. UNESCO adopted the convention as a way to ensure that underwater archeological sites were protected in situ (in their underwater location), although there are a few maritime and archeological museums that hold significant artifacts from the ocean. Another reason to preserve these sites in the sea is to honor their role as underwater graveyards, such as with the wreckage of the Titanic. Indeed, many of the sunken sites on the heritage list function "as a time capsule, providing a complete snapshot of the life on board at the time of sinking."

Scuba diving near many of these heritage sites is not allowed or near impossible. But since wreck diving is a popular and exhilarating adventure activity, UNESCO recommends four diving trails in Australia, Florida, Israel, and Sweden and has drawn up a Code of Ethics for Diving on Submerged Archeological Sites for divers who do want to explore wrecks and ruins. For the rest of us, there's this gallery of some of the amazing artifacts resting on the ocean floor.

Gallery: UNESCO Underwater Cultural Heritage Sites

[All photos: UNESCO]

Filed under: Arts and Culture, Scuba Diving, Photos, Ecotourism