Desigining an underwater city, a la Rapture

In a couple of months, I'll be running a TTRPG intended as a crossover between Bioshock and the Chthulu mythos (plus a third, but I won't mention it here lest my players see it). The basic premise is that, at the dawn of the 20th century, R'lyeh rises, and alien forces rain down from the skies, rendering the surface uninhabitable. Humanity flees to a couple dozen bottle cities scattered beneath the oceans, as well as maybe a dozen more deep underground. Several hundred years pass; these cities lose contact with each other, and their inhabitants forget that they're not alone, or that there was ever any other way of life.

The players are going to be denizens of a London-sized underwater sprawl, a set of massive enclosed domes built from a combination of early-1900's tech and eldritch machinery. I haven't designed anything like this before, so are there any suggestions or resources for such a project?

Dunno if it's relevant (3.5 material), but this may be of some help, good for anything with a steampunk edge and integrated magic systems.

Honestly though, unless you can give a little more help/idea of what you need the resources for, it's kinda hard to help. I guess a listed system (D20, D10, D6, freeform, etc) would be a start...?

I'd suggest going oldschool for inspiration though, read 20,000 Leagues Under The Sea, The Time Machine, maybe something slightly more abstract like The Chrysalids (good for an idea of degenerating social structures in isolated post-catastophe settings), and any other proper old sci-fi/fantasy you can find. I'd say the overall feel of the setting is going to be vital to making a premise like this work, it needs to be a rich, detailed and functional environment.

There are a lot of stories based around semi-isolated post-apocalyptic communities. Here's a small list:

• The City of Ember
• Fallout 1 (also 3, and every other game in the series features vaults)
• FreakAngels
• Bioshock
• Bioshock Infinite
• Nausicaa of the Valley of the Wind
• Trigun
• The Matrix
• Final Fantasy: The Spirits Within
• Half-Life 2
• Homeworld
• Mother 3
• Metroid Prime (Chozo lore logs, also a few of the other civilization logs in the series)
• Gears of War
• The Rifters Trilogy (not for anything societal, but for the in-depth description of how the rifters are cybernetically and genetically adapted for deep-sea life)
• Fine Structure

As for a city at the bottom of the ocean, I see two problems:

• Where do you get the power to run your greenhouses and keep everybody warm?
• Where do you get your air from?

These can actually be solved together. As you've probably already figured out, geothermal energy is really easy to work with at the bottom of ocean trenches. It can also be directly harnessed to heat habitats, keeping everyone warm. You may also have major temperature variations across a settlement, with places near the power pipes unbearably hot and the less-inhabited outskirts almost freezing cold. Also note that because of the pressure ice will form at much lower temperatures. Ice may be unheard of.

http://en.wikipedia.org/wiki/Deep_ocean_water

There are two ways to get oxygen. One is through electrolysis, which is easy since you have an infinite supply of geothermal energy, and it produces hydrogen fuel as a byproduct (useful if you have fusion reactors, less useful if you burn it or use it as a chemical). The other is simply by having enough greenhouses to recycle your carbon dioxide.

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Originally Posted by Thomar_of_Uointer

These can actually be solved together. As you've probably already figured out, geothermal energy is really easy to work with at the bottom of ocean trenches. It can also be directly harnessed to heat habitats, keeping everyone warm. You may also have major temperature variations across a settlement, with places near the power pipes unbearably hot and the less-inhabited outskirts almost freezing cold. Also note that because of the pressure ice will form at much lower temperatures. Ice may be unheard of.

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Wouldn't building in a deep ocean trench create huge problems with making your dome hold up to the pressure compared to building in shallower water?

I'd go with nuclear fission or fusion. You can extract the fuel for either one from ocean water, and you don't have to be in a trench to do it.

Another is food:


Alge vats are nearly traditianal now (fallout uses something similer), but you can always go with a actual slime (totaly not eldrichy at all) filled with nutriants and such. I doubt that there's many large animals brought down to eat, but it would take a special sort of crop to cultivate in a domed city in a ocean trench. Seaweed?

um a few minor points.
Fusion works as a power source-can get the hydrogen from electrolysis and have plenty left over to power the city. Fission need rare metals (uranium or thorium mostly) which sorry to say are not found in sea water in the concentrated high enough to matter, unless you are at some fumerole at which point geothermal is easier anyway. Also there are current generators. Basically huge windmills pushed by water currents instead of wind.
Also on the subject of ice. While water ice won't be an issue Methane Ice very much can be depending on the local geology. If there a seep of the stuff the Methane Ice can build up at incredible rates becomes weird slush and does wonders to block intake vents, hatches and the like. But no it doesn't float around like and iceberg.
also in terms of resources anything that in an antarctic research station, space station, or space outpost may be relevant- Not just for the life support systems but also giving hints on the sense of isolation and claustrophobia that seems to go with such a game.
and good luck.

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Originally Posted by sktarq

um a few minor points.
Fusion works as a power source-can get the hydrogen from electrolysis and have plenty left over to power the city. Fission need rare metals (uranium or thorium mostly) which sorry to say are not found in sea water in the concentrated high enough to matter, unless you are at some fumerole at which point geothermal is easier anyway.

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Yes they are. Using currently demonstrated tech, the total cost of fission power from seaborne uranium is, at most, 50% greater than using surface-mined uranium. Combine it with a fast breeder reactor and it's basically the same price.

Not to burst too many bubbles guys, but the OP stated turn of the 20th, not turn of the 21st. You're discussing tech 100 years ahead of anything the setting should be producing, whereas ocean current turbines and geothermal would supply everything needed and more.

Separate issue, what happens to all those lovely folk who wish to explore beyond the city? If these people have been down here for more than a decade or so, I can GUARANTEE you at least one person has left to investigate elsewhere. Humans do this, all the time, even when (or especially when) they shouldn't.

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Originally Posted by asnys

Yes they are. Using currently demonstrated tech, the total cost of fission power from seaborne uranium is, at most, 50% greater than using surface-mined uranium. Combine it with a fast breeder reactor and it's basically the same price.

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I stand updated and much pleased.

<herp>I completely forgot about this thread.</derp>

Commence the wall of quotes.

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Originally Posted by Veklim

Dunno if it's relevant (3.5 material), but this may be of some help, good for anything with a steampunk edge and integrated magic systems.

Honestly though, unless you can give a little more help/idea of what you need the resources for, it's kinda hard to help. I guess a listed system (D20, D10, D6, freeform, etc) would be a start...?

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I'm pulling together a FATE derivative for this, but material from any system is cool. I'm good at extracting the relevant parts.

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I'd suggest going oldschool for inspiration though, read 20,000 Leagues Under The Sea, The Time Machine, maybe something slightly more abstract like The Chrysalids (good for an idea of degenerating social structures in isolated post-catastophe settings), and any other proper old sci-fi/fantasy you can find. I'd say the overall feel of the setting is going to be vital to making a premise like this work, it needs to be a rich, detailed and functional environment.

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That's the idea. Reading list appreciated.

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Originally Posted by Thomar_of_Uointer

There are a lot of stories based around semi-isolated post-apocalyptic communities. Here's a small list:

-snip-

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Also appreciated.

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As for a city at the bottom of the ocean, I see two problems:

• Where do you get the power to run your greenhouses and keep everybody warm?

These can actually be solved together. As you've probably already figured out, geothermal energy is really easy to work with at the bottom of ocean trenches. It can also be directly harnessed to heat habitats, keeping everyone warm. You may also have major temperature variations across a settlement, with places near the power pipes unbearably hot and the less-inhabited outskirts almost freezing cold. Also note that because of the pressure ice will form at much lower temperatures. Ice may be unheard of.

http://en.wikipedia.org/wiki/Deep_ocean_water

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Aye, deep sea vents are the way to go. Fusion power is out, at least for this arcology.

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• Where do you get your air from?

There are two ways to get oxygen. One is through electrolysis, which is easy since you have an infinite supply of geothermal energy, and it produces hydrogen fuel as a byproduct (useful if you have fusion reactors, less useful if you burn it or use it as a chemical). The other is simply by having enough greenhouses to recycle your carbon dioxide.

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Electrolysis works. Small greenhouses are present, but not at the scale to provide sufficient oxygen for a compound of about two million. Too much greenery might make things cheerful, and we can't have that.

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Originally Posted by asnys

Wouldn't building in a deep ocean trench create huge problems with making your dome hold up to the pressure compared to building in shallower water?

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Right, which is why I'm planning clusters of smaller domes instead of a single large one. It's also about 3.5km down, not the bottom of a trench, which helps with the structural issues.

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I'd go with nuclear fission or fusion. You can extract the fuel for either one from ocean water, and you don't have to be in a trench to do it.

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Again, no nukes. I'll get to why in a bit.

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Originally Posted by Pokonic

Another is food:

Alge vats are nearly traditianal now (fallout uses something similer), but you can always go with a actual slime (totaly not eldrichy at all) filled with nutriants and such. I doubt that there's many large animals brought down to eat, but it would take a special sort of crop to cultivate in a domed city in a ocean trench. Seaweed?

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Algae, algae, algae. Also fish farms. And algae.

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Originally Posted by sktarq

um a few minor points.
Fusion works as a power source-can get the hydrogen from electrolysis and have plenty left over to power the city. Fission need rare metals (uranium or thorium mostly) which sorry to say are not found in sea water in the concentrated high enough to matter, unless you are at some fumerole at which point geothermal is easier anyway. Also there are current generators. Basically huge windmills pushed by water currents instead of wind.

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Oooh, I didn't even think about current power.

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Also on the subject of ice. While water ice won't be an issue Methane Ice very much can be depending on the local geology. If there a seep of the stuff the Methane Ice can build up at incredible rates becomes weird slush and does wonders to block intake vents, hatches and the like. But no it doesn't float around like and iceberg.
also in terms of resources anything that in an antarctic research station, space station, or space outpost may be relevant- Not just for the life support systems but also giving hints on the sense of isolation and claustrophobia that seems to go with such a game.
and good luck.

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Noted, and thanks.

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Originally Posted by Veklim

Not to burst too many bubbles guys, but the OP stated turn of the 20th, not turn of the 21st. You're discussing tech 100 years ahead of anything the setting should be producing, whereas ocean current turbines and geothermal would supply everything needed and more.

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Tech level is an obstacle, but not an insurmountable one. Many of the habitats were built partially from eldritech, or are actually long-abandoned alien facilities. I don't want nuclear power because, barring a (highly-unlikely) catastrophic failure, it's too reliable for my purposes. The place is several centuries old, and needs to feel as if its decaying. It's sustainable, but probably not for much more than another century or two.

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Separate issue, what happens to all those lovely folk who wish to explore beyond the city? If these people have been down here for more than a decade or so, I can GUARANTEE you at least one person has left to investigate elsewhere. Humans do this, all the time, even when (or especially when) they shouldn't.

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Oh, certainly, though the hostility of the environment helps to discourage them. The deep ocean is boring, and the majority of people who make local jaunts outside don't see much. Occasionally, you have people who claim to have seen fishmen or other weird creatures dart in front of their lights, but few believe them. Curiously enough, though, any who venture more than 5km from the city are never heard from, and no wreckage is found.

I would expect that humans would undergo some significant physiological alterations, such as albinism. Also, the Biosphere experiments show that it's practically impossible to build a working ecosystem that's completely self-sustaining. This won't necessarily wreck the setting, though. In fact, this could play very well into the feeling you wanted of the setting falling apart. Perhaps there aren't enough nitrogen-fixing bacteria and the absence of nitrates is causing the algea vats to fail, or perhaps there aren't enough predators for the algea and it's overgrowing some abandoned domes and spiking the oxygen level.
Furthermore, keep in mind that without sufficient sunlight, most of the humans would probably have Vitamin D defficiency, which leads to rickets and osteomacalcia (disorders that soften the bones.)

As to the above mutations. In a world with limited breeding partners deep under the sea by a group of people who are survivors from the age of eugenics who were driven to this state via Cthulu and/or similar horrors I don't see such mutants surviving very long. Certainly not being allowed to breed. Which coud lead to all sorts of issues-basement dwelling mutants. Mutants as forced labor for semi suicidal missions etc.
As for health issues. Vit D can be made in the lab quite easily. Though access to such lab made vitimins could be a plot device-status mark etc. Think vit-D fortified milk.

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Originally Posted by sktarq

As to the above mutations. In a world with limited breeding partners deep under the sea by a group of people who are survivors from the age of eugenics who were driven to this state via Cthulu and/or similar horrors I don't see such mutants surviving very long. Certainly not being allowed to breed. Which coud lead to all sorts of issues-basement dwelling mutants. Mutants as forced labor for semi suicidal missions etc.
As for health issues. Vit D can be made in the lab quite easily. Though access to such lab made vitimins could be a plot device-status mark etc. Think vit-D fortified milk.

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I was thinking of the albinism and other mutations as affecting nearly the entire population, rather like what has happened in the real world (Caucasians all have pale skin, Africans all have very dark skin, etc.) The vitamin-d supplements would be a logical reaction to the deprivation of light, and I think they would make an excellent plot point.

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Originally Posted by ReaderAt2046

I was thinking of the albinism and other mutations as affecting nearly the entire population, rather like what has happened in the real world (Caucasians all have pale skin, Africans all have very dark skin, etc.) The vitamin-d supplements would be a logical reaction to the deprivation of light, and I think they would make an excellent plot point.

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That sort of uniform genetic preference in a people takes a good couple of thousand years (about 100 generations or so) at the bare minimum. Albinism is more likely to an extent, since less pigment would form reactively on account of the lack of sunlight, so very pale skin would be common, but pigment (and the ability to produce it) would still exist within the body. I'd expect any obvious mutations to be a result of an external influence, perhaps a bacteria which grows in the air recycling system, or a synthetic nutritional supplement in the food algae which had unforeseen consequences.

Of course, you could go full-on crazy and have some sort of gene therapy designed to assist with deep-sea living. That's a whole can of worms waiting to be popped open right there, but again, probably not appropriate for the period in which these habitats were formed/settled. The eldritch angle offers options for this I suppose, but it all depends on how much 'Eldritch Tech' you really wanna introduce.

The question is, how much time has passed since they descended into the underwater cities?

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Originally Posted by Veklim

I'd expect any obvious mutations to be a result of an external influence, perhaps a bacteria which grows in the air recycling system, or a synthetic nutritional supplement in the food algae which had unforeseen consequences.

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And considering how incredibly complicated God's designs for the ecosystems are, and how humans have tried and failed several times to properlty duplicate such engineering (the biosphere experiments), I would expect there to be several such unforseen consequences.