MONKEY MEMO
Always keep in mind, the difference in water-levels. A map will change considerably, when you go back in time.
The underwater-structure at Yonaguni is debated. Is it man-made or is it natural rock. Never mind, when we go far back in to time, let's say 8000 years ago, the area would be dry, inhabited and this intriguing structure would be a centre of worship.
Consider climate-change. Ancient settlements are found on Greenland, where the ice has retreated. The Sahara-dessert once was a green and lush area, with rivers, lakes and abundant wildlife. How do we know? Because ancient artists painted it on the cave-walls.
Thirdly; remind yourself, that the earth beneath our feet is hollow. There are ancient caves discovered all the time. Beneath ancient cities (Jerusalem but New York, as well. It's an old and once mighty place) and monuments (the Gizeh-complex; where near the Sphinx archeologists dig for the Atlantean “Hall of Records”). you can find immense underground-tunnelsystems. In meso-America we find a combination. Underground tunnels, caves and temple-complexes, that are flooded!
Divers retrieved artifacts, that are said to be 18oo years old. In those days the temple was in full use. Even remains of human sacrifice were found.
In the meantime, the Roman legions conquered England.
YONAGUNI, UNDERWATER STRUCTURE