Yonaguni submarine ruins
Terraced formations were found near the island of Yonaguni (Japan) by divers in 1986. The submarine formations are in large clusters up to 5 floors high. Artifacts were found that prove the existence of people in those places.
In spite of this fact, scientists still argue about the origin of the pyramids. If we suppose that these formations are man-made, they belong to the preglacial civilizations.