The idea of these structures came to my mind when reading about the vast amount of mineral resources in the bottom of the ocean. I thought that, in order to have easy access to those resources, this kind of structure could perhaps be more practical than completely underwater structures, which is what we typically see in movies and books. In my structures, it's much easier to get in and out, for example. No need to take a submarine to go to work, just fly into the city.

People would actually have the benefits of living underwater with the benefits of direct contact with the atmosphere and sunlight. So, why not have a complete mining city in this way? Or even a multitude of them?
(Note: I started this image many weeks ago, but then interrupted it to make some other images. I'm always jumping from unfinished piece to unfinished piece... This one
[link] was one of them. I used here the same basic concept at a much smaller scale.)
My main images with colonies:
The Colony:

Caves of Tau Ceti:

Home away from home:

Shores of Orion:

This image is also another take on my concept of micro-worlds, a concept on which I based several images:
Micro-world of Soul-Sphere:

Micro-world of Thales:

Rendered in Vue, as always.
Or maybe this would be a window-dresser to the gates of hell, sucking people in for cheap labor underground?
Very cool concept, and with the right materials, this might be possible in the future?
But I have a question...
Since we can see the pipes underwater, how come we can't see some more of the structures?
That's a good question, I'm not sure about the answer either. That kind of things is handled by the software, when it's rendering. I'll have to check that.