Under Water River Cities:

I've never really thought about under-ocean rivers that may have been not under the sea long ago. It is true, like you said, that they find things under the water in different places around the world, including places in Europe as well.

History in the Water

There is so much history in the water.

History in the Earth

Beyond that I would love to see what might be inside caves and deep inside the earth. It may be a little hollow and probably not flat but who knows. I really would like to investigate what might be found alongside under water rivers as modern big cities and ancient cities and civilizations would generally be near rivers.

Cities Near Underwater Rivers

That means we can probably find cities near rivers inside the ocean even.