If your looking for an underwater/space spawn/hub or base for your project this one is a good generic starter. You will have to do your own decorations.
Need a larger version?
You can find my underground compound 550x550 map with 41 rooms here

This Is an underwater colony I created for fun. I didn't notice many builds like it and decided to upload it. Maybe one day ill use it on a server.

Colony has 13 glass sphere rooms
1 Main room - 50 block radius/height
4 Secondary rooms - 25 block radius/height
8 small rooms - 10 block radius/height

Dimensions are approximately 300x300

Coordinates - centered on [0,0]

All rooms are connected with glass tubes.