Place
Doggerland
A real inhabited landscape under the North Sea, drowned as the ice-age seas rose.
Max Naylor, “Doggerland”, CC BY-SA 3.0, via Wikimedia Commons
It shows that parts of the prehistoric human map are missing, and underwater. It has not produced an advanced technological civilization. It is not Mu and it is not Atlantis. It is the ground picture of land the sea took.