Beneath the Crust

A mysterious look into a world where the planetary crust has become like islands on top of what appears to be a metallic structured layer with deep turbine holes.

What is down there? What does it do? What are those people doing? and why the heck are they so relaxed about all of this!? Question after question, I want this to make people ponder what it all means. Why is the metal surface so clean? Maybe there are scheduled floods where the oceans get pushed back up to the surface—that's my theory.