Yonaguni Monument, Japan
Discovered in 1987, the Yonaguni Monument in Japan has become a popular attraction for divers. This structure is comprised of mudstone and standstone, and it’s presence has sparked a lot of debate since its discovery. Experts can’t come to an agreement on whether this structure is man-made or natural, but the pillars and columns located on the monument seem to suggest that it was crafted by human hands. This is a popular tourist destination that you can check out for yourself the next time you’re swimming in the waters in Japan.