One of the recent talks regards expanding our cities to colonize the oceans, which many find to be more feasible than colonizing another body in space. So far, we have not gone as building a permanent, metropolitan establishment, but when that comes, some issues obviously need to be addressed.

Fishing and greenhouse farming have been considered, so finding food is not a problem.

Other problems are not so straightforward to solve. In the maximum depth of 350 feet, pressure is added, perhaps close to human tolerance, so what our main facilities need is an architectural shape best suited to withstand that kind of pressure. By choosing the three basic shapes--pyramid, box and dome--which one suits maximum?

In relation, glass does not react well to added pressure, either. That's why deep-sea diving submersibles have thick windows that are small in area and/or circumference. At a maximum depth of 350 feet, would a window in a permanent underwater city also need to be small and thick, too? If so, by how much?

Certain materials withstand pressure differently. Roman concrete has this unique ability to harden as it gets older and keep water out, which may explain how it has survived the past 2,000 years. Would this work in a marine city with a maximum depth of 350 feet, or would something else make for a more durable foundation?

Another problem is how to get a constant supply of oxygen. I could personally suggest planting each main facility with a chimney tall enough to break the surface, but is that feasible?

If one wants to spend the rest of his life beneath the surface, he would prefer to be dry. So how does one open and shut doors without drowning the entire corridor in the process?

The one final issue is finding fresh, drinkable water. I have no idea how that could be accomplished.

How would all those listed issues be addressed and solved?


closed as too broad by bilbo_pingouin, James, Hohmannfan, a CVn, HDE 226868 Jun 16 '16 at 20:58

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    $\begingroup$ Those are many questions at once. I think that would make an interesting series of questions, but all at once is quite broad. Could you edit it to focus on one site first? Plus "best", "max" should usually be avoided, or the metrics to be used should be well defined. $\endgroup$ – bilbo_pingouin Jun 16 '16 at 20:06
  • 1
    $\begingroup$ I don't have the patience to ask it piecemeal. $\endgroup$ – JohnWDailey Jun 16 '16 at 20:39
  • $\begingroup$ @JohnWDailey nothing to do with your level of patience I guess, but if you narrowed it down like bilbo is suggesting you might also get more interesting and detailed answers. Patience is an issue for answerers too. $\endgroup$ – Martine Votvik Jun 16 '16 at 22:24
  • $\begingroup$ When I have got a written project in the process of being re-edited, I can't afford to be patient. I'm having marine cities in this alternate Earth, and I need to know ALL of the workings. $\endgroup$ – JohnWDailey Jun 16 '16 at 22:31
  • $\begingroup$ The SE network is not a place where you should be expecting fast answers. Posting an SE question is typically a last resort. If you're in a hurry, perhaps you should do the research yourself. $\endgroup$ – Aify Jun 16 '16 at 22:41

Plants turn carbon dioxide into oxygen, given light etc. The main thing you didn't address is power. Assuming you have power, nuclear would work pretty well, you use that to generate steam and/or electricity for heating and desalinating seawater. There are a number of different methods for removing the salt from seawater.

As for pressure, if you don't need many frequent trip to the surface, just go with air the same as the water pressure at that depth. That lets you have open pools to the outside without flooding, and considerably fewer problems with pressure crushing your stuff. The downsides are: you must decompress on the way back to the surface, and use a different air mixture while down there.

edit: To clarify the not crushing you stuff comment. If the pressure inside the living area is the same as the pressure outside, then there isn't a great deal of stress on the building materials due to a pressure difference. Depending on how tall your structures are, there will be some difference due to the differences in density of water and air. But you won't need super thick windows and small spherical chambers, it's still a good idea to have water tight doors between compartments and levels, but you won't have to deal with 350' worth of water pressure difference.

  • $\begingroup$ I'm afraid I am not following you. $\endgroup$ – JohnWDailey Jun 16 '16 at 20:40
  • $\begingroup$ Which part? The pressure part is fairly simple, you equalize the pressure in the air filled areas with the outside water pressure, no pressure difference, no flow. $\endgroup$ – Seeds Jun 16 '16 at 20:43
  • $\begingroup$ I still don't understand about how a permanent resident is going from door to door without getting wet. Open pools without flooding? What's that mean? $\endgroup$ – JohnWDailey Jun 16 '16 at 22:33
  • $\begingroup$ It's like a swimming pool, but with no bottom, open out into the ocean. The air pressure keeps the water out. (Think a cup turned over trapping air) As far as internal design, I would think hallways with room off of them, like hotels and apartments, or modular with individual units linked to common travel-ways. You could have groups of units that require swimming to get between, but there is no reason you'd have to. $\endgroup$ – Seeds Jun 17 '16 at 14:43

Not the answer you're looking for? Browse other questions tagged or ask your own question.