This may be my final installment for an underwater base. This one is larger at 550x550 with 41 rooms.
Find my 300x300 underwater colony with 13 rooms here.

If your looking for an underwater/space spawn/hub or base for your project this one is a good generic starter.

This Is an underwater compound 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.

Compound has 41 glass sphere rooms
1 Main room - 60 block radius/height
4 Main hall middle rooms - 40 block radius/height
4 Main hall end rooms - 20 block radius/height
8 Outer Circle rooms - 15 block radius/height
24 small rooms - 10 block radius/height

Dimensions are approximately 550x550
Coordinates - centered on [0,0]
Warm ocean Biome
Kelp and coral fans surround compound

All rooms are connected with glass tubes.