Japan's Yonaguni Underwater Ruins, 10,000 years old

Yonaguni's seabed contains what appear to be ruins of a previous glacial age and traces of terrestrial flora, fauna and stalactites that form only on the surface. These suggest that these alleged ruins are more than 3,000 to 10,000 years old, which would make them the world's oldest.
The fame of Yonaguni island began in 1985, when a Japanese marine explorer, Kihachirō Aratake, by chance discovered a set of very singular architectonic structures allegedly belonging to an ancient civilization and previously unknown in archaeology and history. Shortly thereafter, a group of scientists directed by Misaki Kimura, of the University of the Ryukyus, confirmed the existence of the vestiges. They appear, at least superficially, to be comparable to the pyramids of Egypt, Mesopotamia, Mexico, and Peru.