Or perhaps...
Created a room that links to another "private Age" when you walk into it. Walk in and you hear a linking noise or some other cinematic where the door closes behind you. Takes you to a "Private" room or corridor in the Age which you can model or make your own in any way you please.

But yeah, I get what you say. First step is the most plausible thing to do first though, what you were saying about the flooded dome that's cracked.
isn't there an animation that shows the "big fish" that's underwater in Ae'gura? Perhaps you could borrow that or manipulate it if you can't create something yourself?
I have to uninstall/reinstall Blender though, so maybe at some point in the future you could send me the blend file for this (in whatever form you choose) so I could merely see this thing O-o