In most representations of mermaid cities, they either live in implausible magical palaces, or in some more or less elaborate cave systems.

Assuming the only difference with our world is the presence of the mermaids (so no magic), and that those follow the typical image of lower part fish, upper part humanoids. That they have brains and intelligence similar to the homo sapiens sapiens.

We can imagine that much in the same way that we spread over the lands, they did over the oceans, from the tropics to the arctic, etc.

I am curious, assuming that the main steps of their technological development is somewhat parallel to ours, how their city would realistically look at the dawn of the 20th Century?

They face some challenges different than ours, namely that digging is harder and they have stronger currents.

I would be interested to know about the different architectures for different geographical areas, but I am primarily interested in the moderate waters of the North-Atlantic Ocean (roughly between the USA and Europe).

  • $\begingroup$ If their intelligence is comparable to ours, they would abandon the sea and live on land. The sea is a terrible place to build a city in. Basically, the only difference is that mermaids can breathe underwater? That doesn't mean they should live under the sea (or on it)! I challenge you to name ONE thing of city life that can be achieved under the sea in a not-crazy way. $\endgroup$
    – DraxDomax
    Commented Dec 2, 2015 at 10:58
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    $\begingroup$ @DraxDomax, well I think that their lack of legs would accomodate better under the sea, than skyscrapers in the middle of land. $\endgroup$ Commented Dec 2, 2015 at 11:07
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    $\begingroup$ @DraxDomax, your friend can live well in a city (in the 21st Century, you'll note that the question was asking for the start of the 20th C.) because we, humans developed housings, then cities and then transportation systems, which ultimately allowed the (in that regard) less fortunate of us. Not sure about wheelchairs in 3000 BC. Or do you mean to imply that even if they found alternative solutions to live underwater, as soon as their technology allowed, they would be getting out on land to build cities as ours? If that's the case, you need to provide more details. $\endgroup$ Commented Dec 2, 2015 at 13:38
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    $\begingroup$ @DraxDomax, "How do they build things underwater?" well that's my question isn't it? You seem to forget that they have always been mermaids. And again, at the beginning of the 20th Century, a large portion of the seas were unexplored. And economically, what makes more sense: adapt the environment in which you live, or move your whole population in a completely new and somewhat less practical environment? I have the feeling that somehow the question I asked does not get to you. The answer did get it though, so it cannot be completely bad. $\endgroup$ Commented Dec 2, 2015 at 14:03
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    $\begingroup$ @DraxDomax Yeah, and why don't fish come live on the surface? After all, there are oh so many plants they could munch on. And they live in cities in modern times! $\endgroup$ Commented Jun 23, 2016 at 3:42

6 Answers 6


I will derive my solution by comparing to real-world precedents, and analyzing how these might be adapted by merfolk. (TL;DR: Rock domes.)

Why do humans have houses?

  • Shelter from the elements. As mentioned in another answer, houses provide protection from storms and from extremes in heat and cold. This may be less important to merfolk, but not entirely absent.
  • Shelter from predators. As much as we once feared the dire-wolf and smilodon, merfolk likely had the same issue with sharks and orcas.
  • Privacy. Humans feel the need to perform acts of ablution, elimination, and procreation away from the eyes of other humans. Let us assume merfolk have the same sense of modesty, so this is a factor.
  • Security. Humans like to accumulate stuff. They attach value to it, and want to keep other humans from readily taking it away. Again, let's assume merfolk have also developed this sense of ownership.

What do humans make houses from?

  • Wood. We can eliminate this as not available to merfolk. Even if they salvaged wood from sunken ships and fallen trees which washed down flooded rivers, it would be in poor condition for use in construction.
  • Mud/ Adobe. Another thing we can eliminate. When baked on land, it is rain proof, but against total immersion it would break down and drift away quickly.
  • Woven Vegetation (thatch). This is plausible, I'm imagining kelp. In fact, sea otters wrap themselves in kelp when sleeping. Primitive merfolk might have copied this and expanded on it.
  • Animal Hides. I don't have any way to back this up, but my gut tells me it is not possible to tan leather when surrounded by salt water. As fun as it is to think of a merman making shark leather, we must eliminate this one too.
  • Bones. Generally not sufficient to make an entire house, but like humans, merfolk probably put bone to good use in tools, decorations, and so on. Bone is better preserved in the ocean than on land, also.
  • Metals. Deteriorates in salt water, so nope.
  • Glass. I'm not sure about merfolk's ability to make glass, so I'm just going to punt this one away.
  • Rock. This is my pick, especially coral rock. Collect it, stack it, and soon you have yourself a nice structure. Mortar is not an option (see adobe above), but it could be reinforced with the kelp-thatch the ancestors used.

What shape are human houses?

  • Tepee/ Yurt. The central timbers lean together to support each other and the surrounding skins. Since we have eliminated these materials, we also eliminate these shapes.
  • Cube-Like. Some human ancestors seemed to heavily favor straight lines and things that were perfectly horizontal and vertical and met at exact right angles. I won't rule this out for merfolk, but I like the next option better, given that merfolk live in a three dimensions and need no concept of "floor."
  • Domes/ Igloos: The weight of the bricks (whether rock or snow) is mutually and evenly distributed, resulting in a sturdy structure. Domes also use space very efficiently. There just must be a Buckminster Fuller amongst the merfolk.

How do we put all of this together?

Most merfolk dwellings consist of overlapping dome-shaped modules. Each module is built from pieces of coral and other rock. Where needed, the coral is held together with by mats of woven seaweed, particularly kelp. They have doors with locks. They don't have what a human would call a "window," since any opening is just another door. The doors might be made of single flat rocks, or perhaps bone. Each door also has curtains, to retain privacy even when left open to let fresh water circulate through. Depending on the fashion sense of the owner, the curtain could just be a simple collection of plant leaves, or strings of shells and small bones.

It isn't clear whether they need any variant of HVAC. As mentioned above, fresh water will circulate if you just leave a few doors open when the current is just right. Whether they have furnaces and how they work could be the subject of a whole other question here.

Larger buildings like office complexes or shopping malls are just larger domes with larger numbers of inter-locking modules. They locate their cities in the places that offer the best conditions, just like humans. That means mild climate, access to resources, and plenty of open build-able spaces. I suspect areas adjacent to- but not directly on- large reefs would be attractive to them.

  • $\begingroup$ How about whale bones? $\endgroup$ Commented Dec 2, 2015 at 17:36
  • $\begingroup$ @SerbanTanasa: Yes, where my answers mentions "bone" it probably means ungulate bones in the human case, and cetacean bones in the merfolk case. I tried to keep it generalized, though. $\endgroup$
    – cobaltduck
    Commented Dec 2, 2015 at 17:42
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    $\begingroup$ You gave me the aesthetically pleasing image of a dozen bubbles connected, only made of coral with bright colors and lots of fish. $\endgroup$ Commented Jun 23, 2016 at 3:45
  • $\begingroup$ the little wood they do get will survive just as well underwater as on land as long as they keep the vermin off of it. wood rots when subjected to repeated wetting and drying, if it never dries out it is fine. $\endgroup$
    – John
    Commented May 5, 2017 at 20:29
  • $\begingroup$ Just look at the homes humans built from mammoth bones for examples of bone housing. $\endgroup$
    – John
    Commented May 5, 2017 at 20:31

As a RPG-writer, I've stumbled with how would my mermaids culture and architecture look for humans. Well, unless your mermaids and your humans are isolated, some things will follow, but the more important one is:

Mermaids won't live in deep waters

As a human-sized fish-mammal hybrid, mermaids are not adapted to living in deep water conditions. They will probably live around beaches, and maybe a bit off the coast, but never on deep, empty ocean. The human body that makes their upper torso doesn't support deep-sea living for long without heavy equipment, and evolution can only take you so far as adaptation goes without making them look like whales or sea-lions. The sea can be really cold, so they will need shallower, warmer waters to thrive. Also, in literature, at least, mermaids go with some frequency to the surface to interact with the surface in a way or another. Don't think of them like the mermaids from the Disney movies or as friends of Aquaman. They are likely to spend a lot of time on land trading, gathering stuff from the beaches, getting sun-baths, luring sailors to eat them alive... mermaid stuff. They are half-human, and they can breath air. They will probably love the warm sun on their skin, the taste of fresh coconuts, or some freshly-cut palmito with their fish. They will love to look to the sky at full moon, and will probably love to sing in the beach, around a fire. You can't sing really well underwater.

I believe that mermaids would start more tribal than humans, at first, like Amazonian or African tribes that develop a bit away from the main bodies of civilization. They will probably be more carnivorous than anything else, since fish is a way better source of fundamental nutrients for mammals of their size than kelp - I imagine their diet being similar to those of dolphins. Since building stuff underwater is hard, mermaids will probably be stuck with living in caves or some rudimentary rock-houses for a while.

That's it, until they see what land-dwellers built.

At the moment the mermaid scouts bring the notice of the majestic human cities near the coast, I believe mermaids will take a great deal of interest on those strange, two-legged creatures and the stuff they build. Their leaders will want those majestic buildings, too, and will, sooner or later, do what humans do best - imitate them.

They will try to simulate what they see on the coast, with their vision on how should things work on their culture. They will probably build hybrid constructions on relatively shallow water, with some parts over and some parts under water. However, this type of building needs materials that are really hard to get underwater, so they will probably need to buy them from land-dwellers. To make that work, your mermaids will need some economical advantage over humans - something that only they can get, it's expensive, and that humans really want. That way, they can buy the materials and hire the work they need to build their coastal palaces, which will be built using granite and similar materials, and adorned with gold and gemstones. Mermaids like some bling, too. Those buildings will probably be made to be used by mermaids, with some capabilities for humans to cross. There is no good to have a sublime palace if you can't show it off to the other people.

Mermaids will probably love wide open spaces, with tons of glass panes for light to shine in, probably emulating how the sun shines through the water. If they do have multi-store buildings over-water, they will use columns of water which connect pools in different floors to go up and down. Those columns could be partially sealed off to prevent water spill, and some crafty use of wind-powered water pumps will make sure the water stays on level everywhere.

The use of hybrid buildings will make a lot of things that are harder underwater way easier. Medical care, for example. If blood spills on land, it goes down to the ground and stays there. If it spills underwater, it goes everywhere, mixing with water and making things really messy. Metalworking and leather working simply don't happen underwater, and so your mermaids will want some surface area to work with those the same way humans do.

Also, electricity and water can go messy really fast, so they will probably be way more wary of electrical power than humans are. If they adopt it, it probably will be restricted to the surface areas of their dwellings, and will not, for obvious reasons, extend to their underwater areas except on some really, really controlled settings for essential stuff - mostly illumination and heating.

So, in essence, instead of deep-water cities, they will probably build coastal, resort-like cities adapted both for them and for humans, which they will probably be contacting often. Their cities will probably be build from the beach towards the sea, and will extend for a while until the water gets too deep to build or too cold to live in.

As a side-note, don't be afraid to build a less-advanced culture for your mermaids. Their problems and environments are different, and so will be their development.

Think of how Hawaii was before the arrival of the foreign people, and how it is now. Seems as a good way to go with your mermaids, I think.

Most important of all, don't let their fish-tails be something restrictive. On the contrary, use them to boost their capabilities, and let them roam the land and the sea in ways that we humans can only dream of. Don't shackle them to the bottom of the ocean. Their voices deserve to be heard, their songs deserve to be listened, and their belies deserve to be full of sailor-meat!

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    $\begingroup$ You truly are a writer. Thank you. It was a pleasure to read and I totally agree with your reasoning - and I like how you don't just restrict, but also provide avenues of creativity. Cheers! $\endgroup$
    – DraxDomax
    Commented Jul 1, 2016 at 13:34

Architecture is a means of providing for a need. For humans, the primary reasons for housing of any kind are shelter, as in shelter from the rain, shelter from the cold, and protection against large predators.

Over time, obviously, housing became more and more complex.

Since you assume your mermaids are pretty similar to homo sapiens, you can assume that their needs will be quite similar, although you will have to account for the absence of legs, and the somewhat wetter environment.

Two things spring to mind there: Mermaids have no need for stairs, and they don't need (much) scaffolding. So, building vertically is easier under the sea than it is on land, although the currents create much stronger lateral forces than the wind does above the surface, which reduces the benefits somewhat.

Something else is important: Human propulsion typically happens with an upright human, while a mermaid, given the water density, will typically travel more or less horizontally, even for short distances. that means, passages can be much lower, but need to be wider to allow for turning.

Finally, a floor is of much lesser importance for mermaids than for us. The only thing one should expect to be truly similar is that a building typically will have an outer shell of walls and roof, to keep out the currents, and predators as well as pests.

You should expect windows, but doors will be shaped differently, especially they don't need to be as high as ours, again because of travel in a horizontal attitude.

You will most likely have means of storing your things, which means chests, cupboards and such, but far less shelves.

And after that, everything else will most likely be left to personal taste.

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    $\begingroup$ I can see a lot of nets for storage, fiber is one of the few things they can get, and unlike on land they have to worry about things drifting away. $\endgroup$
    – John
    Commented May 5, 2017 at 20:34

Interestingly, I'd think that much aquatic architecture would attempt to build down as well as up. The oceans are full of caves, caverns, and bottomless chasms: these should provide both protection from predators and enemies and a great three-dimensional foundation on which to build your city.

With this in mind, I'd like to think that many buildings would be supported by a series of ropes. This would make it easy to add new buildings to an existing structure, or move buildings to other structures with minimal demolition. As mentioned in other answers, things like stairs and doors become mostly useless underwater, so what might seem to us to be a confused interconnected mass of buildings might end up making a lot of sense to merfolk. For instance, big ropes supporting some of the city's largest and heaviest structures may be used as an analogue to highways, while smaller ropes help serve as landmarks when navigating more suburban areas. If electricity gets introduced, it shouldn't be hard to attach wires to the ropes to connect all buildings to the power grid.

The problem I can see with this kind of city is sanitation. Without a rigid structure upon which to lay your piping, it may be difficult to keep things properly plumbed. Though now I'm wondering if our concept of plumbing would even work underwater; maybe they just use outhouses.

  • $\begingroup$ You'd make your rope from kelt? Or how do you solve that problem? $\endgroup$ Commented Dec 3, 2015 at 7:14
  • $\begingroup$ @bilbo_pingouin Probably some combination of plant and/or animal fibers, yes. Rope is very useful (for instance in nets, which could prove very useful as well), I'm sure merfolk will find ways to make it. Maybe even some imports from the surface. $\endgroup$ Commented Dec 3, 2015 at 14:04

While the building construction aspect is covered, if truly mirroring the dawn of the 20th century then the city planning would be happening at the point where the car was replacing the horse and buggy for us. Roads weren't paved, sidewalks when available were wood and to keep you out of the mud and horse-poop. Where big cities had plumbing in the downtown core and sewage systems, but the power grid was generally not yet there.

If you are really going to mirror that, you may want to consider what the mer-folk used for draft animals, what they farmed and how they contained livestock that moves in three dimensions.

And most marine life tends to fall within a fairly narrow band of water depth to meet their light / temperature requirements. Are your mermen top-of-ocean dwellers? Or deep-sea creatures?


Mermaids and merman in my story would preferably live closer to the surface because as with all mammals, they need oxygen. So their houses would be built by adapting the coves and caves underwater to reach their sheltering desires. No need for floors and they would make good use of underwater plants. As they do not want to draw attention from Humans, their buildings would be a bit hidden. I like the bone idea too.

  • $\begingroup$ This is more of a comment on existing answers than an answer by itself. $\endgroup$
    – sphennings
    Commented May 5, 2017 at 20:34
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    – Secespitus
    Commented May 5, 2017 at 20:56
  • $\begingroup$ I edited this answer by deleting the preamble, to make it read more like an actual answer and less like a commentary. While it's great that you find the site helpful, we prefer that you do so by contributing good questions and answers, and voting on other peoples' posts (once you have earned the reputation required to do so, which should happen quickly if you contribute quality material). Do make sure that your answers actually answer the question as asked, rather than discuss something unrelated to what the OP is asking about, but feel free to draw from your own work as inspiration. Have fun! $\endgroup$
    – user
    Commented May 5, 2017 at 21:46

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