Let's imagine that, keeping the familiar shape of the real world map, seas and continents are interchanged. Mainland becomes sea and oceans become continents.

We may also imagine that mountain ranges are sea trenches and vice versa -- you would have a Himalaya Trench north of the Indian Gulf, in the Great Asian Ocean, the deepest part of the world's oceans, and a Mariana mountain range, towering at nearly 11 Km above the nearest sea (New Guinea Lake?).

To begin with, a rough outline of a flooded old Europe. One needs a little mind click to get the idea, I think. Just imagine the countless alternate historical and political possibilities. And the climate, of course. Try it at home with you own continent!Land-is-sea-and-sea-is-land.jpg