In my fantasy setting there is a species of merfolk who live in the ocean. They have hands with human level of dexterity and can live completely underwater.

I would want to ask a question about what kind of houses merfolk would be able to build, and how they would be constructed and kept in place.

The merfolk have contact and trade with a nearby human civilization who are technologically as advanced as mediterranean civilizations during classical antiquity, the 500s B.C., however most materials traded from humans are available to the merfolk "upper classes" while the lower class merfolk for the most part have to use materials gained from their natural environment. Finding suitable building materials underwater is difficult but I've decided that rocks and mats woven from seaweed and kelp would be one of the few suitable ones that can be made naturally. However, I'm not sure about the shape of the houses nor how such a building could be kept in place, since on land most dwellings made of rock uses cement/some kind of glue for keeping the bricks together, and that doesnt work underwater.

Something the shape of an igloo but composed of stacked rocks would make the most sense, but unlike snow, stone isnt malleable and I'm not sure if it would be structurally sound without some adesive holding the "bricks" together.

As for the roof, i'm imagining it as a mat of woven or thatched kelp laid over the walls, but it has to be tied to something so it doesnt float away.

  • 1
    $\begingroup$ In what kind of waters do they live? Tropical, mediterranean, atlantic, arctic seas...? This can drastically change the "natural resources" available as you could build an house inside an iceberg or perhaps take advantage of corals. $\endgroup$ Jul 22, 2021 at 21:58
  • $\begingroup$ They live in a Mediterranean environment, so Hard corals are available. $\endgroup$ Jul 22, 2021 at 22:03
  • 3
    $\begingroup$ Does this answer your question? Mermaid architecture $\endgroup$
    – rek
    Jul 23, 2021 at 5:00
  • $\begingroup$ How is this a duplicate? This question limits technology to 500 BCE Europe, while the other one asks '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?'. Are you sure there is no difference between building technologies available 2500 and 100 years ago? $\endgroup$
    – Otkin
    Jul 23, 2021 at 20:39
  • $\begingroup$ @Otkin The answer to that question covers the parameters of this one. Didn't you read it? Coral domes, doors of bone, woven seaweed. Hardly Nuclear Age building techniques. $\endgroup$
    – rek
    Jul 23, 2021 at 21:14

2 Answers 2


What do you use a house for?

The biggest question is: what do you need a house for? what are the social, environmental or psychological reasons for having a house? Humans have houses for many reasons, and your merfolk may have different ones. You may come to find merfolk need NO houses, or live in dorms, or use individual pods. Form follows function, so ask why they have houses.

  • Humans have houses to protect from the environment, but anyone dealing with depths is likely to be more temperature-tolerant. But merfolk may need temperature-controlled environments for special functions like reproduction or child-rearing. Places may need to be sheltered from currents, or create still areas where debris can settle out of the water for whatever reason. The nature of water makes temperature control tricky if water can circulate. I don't know what heat sources merfolk might have, but keeping spaces warm might involve considerable complex engineering.
  • People want houses to protect from violence. That might mean saltwater piranhas, giant octopi, or rival warring merfolk. the shape of the dwelling will be defined by what it is you are trying to keep OUT. Fine woven mesh protects from small things, while huge stone spikes might be needed to keep out a Kraken.
  • Humans use housing for privacy. They live close to other people, but don't want others to watch them all the time. For visual privacy, simple woven mats might suffice. Sound travels oddly in water, so soundproofing might look very different for merfolk. The bigger the community, the more merfolk might not want strangers staring at them. If merfolk evolved as nomads and live now in cities, pretending your neighbors AREN'T next door might be crucial. Or, maybe they have no privacy in families but keep out strangers. Do your merfolk value secrecy? Do they commit crimes, defy the government, or live in communal utopia? Do the rich merfolk want to conceal their wealth so as not to anger others?
  • Humans use houses to store stuff they don't want lost/eaten/stolen. Keeping resources contained is an undervalued thing. Do your merfolk steal? Do fishes sneak around trying to eat their food? What kind of threats do you need to deal with for your stuff?
  • People want houses to show off. Perhaps rich merfolk build houses out of stone because it's difficult, not because of practicality. Keeping up with the Joneses is a big deal, and if you're from a rich family, you might be more reproductively successful. Or merfolk may desire to impress humans, despite not caring for houses themselves. They may want houses because they imitate humans whom the perceive to be rich, successful, or influential.
  • Houses are places to interact in controlled environments. Do your merfolk mate publicly? privacy for mating could be important. Do they need someplace to contain sperm so it doesn't randomly impregnate strangers? Do they invite humans over? If so, dry or semidry parts of a home are crucial. A half-flooded top floor could be a hosting place. Do they have special work functions (like smelting on the surface, while sitting protected from heat in the water)? This will radically affect how these places are shaped.


People build first with what they have, then with what serves the function. Chipping stone in an aquatic environment might be a high-resistance task, but saws would have continuous cooling. Metal tools could be expensive or tricky. Wood often rots more slowly in the water, but could be expensive and vulnerable to parasites. Growing corals and plants to fit needs would be an elegant solution to many problems, but your merfolk would need a fair amount of biological technology to do so. However, given an understanding of selective breeding, they could guide various types of mangroves, corals, kelps, and the like to do their bidding.

Shells might function as direct components of walls, OR the calcium carbonate could be used for some type of cement. Perhaps the glues used by some kinds of clams and barnacles could allow walls to be grown from these organisms, or use these organisms to bind together other hard materials into solid structures. A barnacle bred to glue things on multiple sides could be the binder for hard material in the environment, from shells to loose stones. Then the irregular parts get filled in with whatever is available.


Your merfolk might extend home up to the surface, and then have no roof. homes might even be hanging down into the water from floats, like curtains weighted with stones or shells. A home then becomes mobile or even migratory like a ship, as needed. Such houses would need an anchor when staying put. If moving against the current but with the wind, sails could be used to guide the house. You could even use them to alternate direction, 'sailing' your town back and forth to keep it in place or following harvests.

I'm guessing due to buoyancy, a lot of the structures would be made of seemingly flimsy materials like kelp. Flexibility might be more important than strength. Solid structures make more sense to keep out predators like sharks and sea monsters, but a lot of big things aren't going to push through barriers they can't see through.



sunken ship


Wood is great stuff to build a house with, on land or in the sea. Maybe even better in the sea because it wont catch fire, although there are shipworms to worry about. Once wood is waterlogged it sinks. The wood of this ship is 500 years old and I think I could make a fine little shack with it. There is a lot of wood on the bottom of the sea. There is even a vogue lately for bringing up those huge old trees that have been underwater for centuries and building with them.

You would need to anchor the wood. That is true on land too! Anchor it with stones, as one does.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .