Were there any people alive?

I have a question that maybe stupid and i could solve by looking myself. But im just curious what you think. Does there live any people in the flooded Hyrule. The place where Dahpnes lives, actually i dont think so as the game doesnt tell you. But if you walk trough the path near Ganon's Tower you see in the distance the giant lands of Hyrule in top-quality. Why did everybody go to the surface if they could live fine in the paradise of Hyrule under water. Just like in Atlantis. Im pretty sure im wrong, but is there a possibility?