These “structures” can be found off the coast of the island of Yonaguni near Okinawa, Japan, and according to the Morien Institute, they “show quite clearly that, during the last Ice Age, civilisation flourished on what were then the coastal areas of the many parts of the world which, despite glaciations further north, still enjoyed a very pleasant, temperate climate. These ancient settlements are proving to have been much more advanced urban cities than current models of prehistory are prepared to acknowledge, but their existence is just as real as the fact that they were obviously flooded during the abrupt end of the last Ice Age, at the Pleistocene/Holocene boundary.”
Or they aren't man-made structures at all, and that in actuality, according to geologist Robert M. Schoch, geomorphological processes such as “natural wave and tidal actionæ” have eroded and removed ”the sandstones in such a way that very regular step-like and terrace-like structure remain.”
Or maybe, as a middle ground between the two theories, the Yonaguni Monuments were at first natural formations but later terraformed, i.e., manipulated and modified by human hands, into ceremonial platforms.
And transoceanic ports?
Pleistocene astronomical observatories?
Or maybe it was the site of a quarry from which “blocks were cut, utilizing natural bedding, joint, and fracture planes of the rock, and thence removed for the purpose of constructing other structures which are long since gone.”
Suffice to say they require further investigation.
So in the meantime, all these photos suggest unambiguously that when the Egyptian pyramids are dropped into the bottom of the Mediterranean Sea, they will remain as enigmatic as they were in the open desert, if not more so. That any other large structures, from the Eiffel Tower to Notre Dame Cathedral to Angkor Wat, are probably better explored underwater, devoid of a totality of experience.
It was BLDGBLOG who once proposed a graveyard archipelago for cathedrals. But how about the Marianas Trench?
In any case, if you'd like to learn more (and can read Japanese), go here. And there's also this flash presentation.