Diego Garcia Has Underwater Base?

Bizarre images from Google earth which seem to confirm that Diego Garcia has an underwater installation of some kind.

Could this be an ultra top secret military base or even possibly an underwater Alien base.

Many conspiracy theorists believe, that missing Malaysian Flight MH370 landed or was forcibly diverted to Diego Garcia by unknown forces.

The United States Navy operates a Naval Support Facility (NSF) on Diego Garcia.

Its also a large naval ship and submarine support base, and has a space-tracking facility.

What do you think of the images?