I regularly see people speaking about the difficulties of technology underwater, and see questions about whether underwater civilizations could produce fire, electricity, etc.. But I haven't seen any talking about what an underwater people would excel at, technologically.

People in different environments sometimes developed skills and technology because of that environment, be it sailing or sword-smithing. Then, while living underwater would hamper many of your technological efforts, surely it would encourage some as well?

I am using mermaids for this question, as there are too many possibilities and questions if it related to any and all underwater life. So let's stick to mermaids that can breathe underwater and above water, for simplicity.

So, what sorts of technology might be accelerated or developed, due to their unique situation?

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    $\begingroup$ Humans are very interested in the water/under-water interface. We travel on it, fish beneath it, and conduct war in both locations. I doubt merfolk would be any different. So, to ask a question, how likely are merfolk to consider humans crunchy and good with ketchup? $\endgroup$ Dec 25 '20 at 6:51
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    $\begingroup$ Cool! Note that the land-to-sea interface is more complex than the land-to-air interface. But I am toying with the idea of harvesting fro the sea surface. If the process of capturing fish is fishing, would the process of capturing humans be humaning? $\endgroup$ Dec 25 '20 at 17:37
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    $\begingroup$ Your real problem is the vast majority of what we call technology relies on fire at some point in its production. There just are not many technologies available for them to accel at. $\endgroup$
    – John
    Dec 25 '20 at 19:32
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    $\begingroup$ Just a thought, but if they developed a civilisation under the water, they would by necessity be really skilled at underwater construction, fire-less material working, Likely organic tools, likely skilled in electro-chemical reactions. Underwater metallurgy, etc. $\endgroup$
    – PcMan
    Dec 26 '20 at 3:22
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    $\begingroup$ phishing perhaps? $\endgroup$
    – abligh
    Dec 26 '20 at 8:47

It seems quite obvious, but fish farming and fishery should be the obvious answer.

We landlings have had a few thousands of years for developing domesticated animals like chicken, sheep, cow, horse and so on, which we use for getting access to meat, while we fish farming has been a rather recent exploit.

For merpeople I would guess the opposite would be true: they would probably have domesticated tunas, salmons and what else, having developed domesticated breeds which can be very distant from the original, living in the wild, ancestor.

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    $\begingroup$ They could also work out self-sustaining hydroponic farms, using the fish to cultivate plant life and crabs which can sustain the fish. $\endgroup$
    – Johnny
    Dec 25 '20 at 6:43
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    $\begingroup$ I'm not sure if this counts as tech. It is industry, sure, but farms of fish don't really put merfolk ahead in any sort of science capacity -- the particulars of farming fish are not substantially different from the issues of other livestock. I'm not downvoting it, but it's a close call. Maybe there's something about 3D fencing? $\endgroup$
    – SRM
    Dec 25 '20 at 11:09
  • $\begingroup$ Aquaculture in general. $\endgroup$
    – Spencer
    Dec 25 '20 at 18:34
  • $\begingroup$ @SRM "Technology" is much broader than machines, it includes stuff like farming techniques. $\endgroup$
    – user253751
    Dec 28 '20 at 12:37
  • $\begingroup$ @user253751 Yes, but I'm not aware of any particularly non-obvious techniques that fish farming requires. The knowledge of breeding schedules, etc., are things that land dwellers have derived, and the proper maintenance of a school is much the same as for a herd of cattle. Can you name me particular technologies that would be developed by the merfolk for fish that would be different from ranchers for cattle? I know a bit about both and cannot name anything myself. $\endgroup$
    – SRM
    Dec 28 '20 at 22:08

Sonics - Many aquatic mammals have complex auditory communications that can travel thousands of miles. They also have complex anatomy that enables them to send and receive these messages.

Mathematics - much of human geometry is based on starting in 1 or 2 dimensions and extrapolating to 3 since we live largely on a 2d surface and our primary visual system is based on 2 dimensional grid of light - we have two eyes but they each are a 2d grid of rods/cones on the back of our retina so our brain creates some 3d information out of two 2d images, but we are still primarily thinking and experiencing life in 2d. Mermaids would have experience living in a 3 dimensional environment, more like birds than land mammals, perhaps with sonic-organs that are built to sense a 3-dimensional landscape. So perhaps they would have an easier time grasping 3 dimensional mathematics and also extrapolating it to 4 dimensions, which would help when comprehending Special and General Relativity. A good example in my opinion of this is how we tried to understand Angles in three dimensions - we simply recorded three 2-dimensional angles for each object, as if we attached 3 high-school math protractors to an object in space (roll/pitch/yaw). But this system can lead to Gimbal Lock which is an unpleasant situation where a navigation instrument gets stuck and cannot determine true orientation in 3d space. Perhaps Mermaids would have come up sooner with Quaternions which can represent 3d orientation without gimbal lock.

Bubble physics - Sonoluminescence is a not-well-understood phenomenon relating to the high energy reactions created when a bubble collapses, sometimes causing the atoms involved to emit light. There is a fringe theory (with some notable frauds causing a loss of interest in the subject) that it may be possible to create nuclear fusion in this way http://large.stanford.edu/courses/2015/ph241/chapa2/

Bioluminescence - many sea creatures are bioluminescent. Perhaps this could lead mermaids to study how light is emitted from biological chemical reactions

Bio electricity - Electric eels have very strong electric fields, perhaps allowing Mermaids to study electricity without having to risk getting struck by lightning as Benjamin Franklin did.

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    $\begingroup$ I may choose this as the best answer. I'll give it a little more time, but I really like this point. $\endgroup$
    – Johnny
    Dec 26 '20 at 2:59
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    $\begingroup$ hey thanks, i also like the other answers too. feels like we have just scratched the surface. there are black smokers, extremophiles, tectonic plates, coral reefs, octopus ganglia, whale fish bubble nets... arctic sea ice... glaciation.. $\endgroup$
    – don bright
    Dec 26 '20 at 3:09

My first thought is they would develop science in anything to do with pressure: Pipes, gasses, biology, etc., as they will be familiar with the bends and what happens when you try to take air deep underwater, and so they they'd likely make good use of buoyancy in their engineering.

For example: Imagine using bags of air to hold up a heavy stone, as you shift it into place (it's still heavy, but now there's no friction with the ground).

Tides would also be an educational tool in the study of pressure, and they may even be able to eventually harness these.

  • $\begingroup$ ...Finding leaks in swimming pools. $\endgroup$ Dec 25 '20 at 18:06
  • $\begingroup$ Some related terms that might be websearched: Hydraulics, Fluid mechanics, Fluid dynamics (incl. hydrodynamics). And when it gets to circuitry/logic, Fluidics. Analogous to how humans live surrounded by atmosphere but have access to water and know a lot about it, aquatic sentient species could develop a lot of knowledge regarding the atmosphere/gasses and even develop vessels to travel in it. $\endgroup$
    – frIT
    Dec 28 '20 at 8:10

Skyscraper-like underwater buildings would have less logistic problems to design: If the mermaids can swim up and down, there is no need for stairs, elevators, or ladders. There is also no need for fire escapes because the risk of fire is very low. However, carving stone would be much more difficult, since hammers would be hard to use underwater. Merfolk can't build with wood, since trees don't grow underwater.

Tunneling to create homes might be a good option, and it could allow quick travel through narrow bodies of land, the equivalent to bridges that humans build.

The lack of fire would make it difficult to smelt metal and impossible to create a combustion engine. Wheels would not be useful for transportation underwater.

The most important invention humans ever made was the spear. This original tool allowed mankind to wipe out their natural predators and rival humans alike, and encouraged the development of language. Spears would also function underwater, and would secure merfolk a place at the top of the food chain.

Humans have domesticated many animals and plants through selective breeding. Merfolk could do the same with underwater plants and animals.

Humans have been using diving bells to travel underwater for thousands of years. Merfolk might be able to do the reverse: Carrying buckets of water up onto land to breathe with. Humans have been extracting resources from the sea since the dawn of time. Perhaps merfolk could take resources from the surface?

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    $\begingroup$ Hey Jafego, thanks for answering, and welcome. I was thinking mermaids could have some uninhabited islands and rocks they'd make good use of. Both for communal purposes like sunbathing, and likely for commercial purposes like starting a fire, drying out materials, and more. $\endgroup$
    – Johnny
    Dec 25 '20 at 7:25

Homo Atlantis A technological overview of Atlantians, also known as “mer-people”

To see how mer-people behave when they are interacting with technology, we need to see that encounters with humans have rarely brought about peaceable exchange. Instead, tales of siren calls widowing brave sailors, and cruel marriage of spheres to the Krakenoid and Cthuloid beings that I dare not mention, we may not assume the Atlantians had similar motives nor devices to us.

This means that they cannot be thought of as joyful Ariels communicating with crustaceans and woeful Danish royalty. These beings live at the extreme pressures of the oceans, as numerous surveys and repeated trawling of the seabed have not yielded as much as a clam bikini.

A much more terrible Reality dawns before us, whence the motives of survival trump every other concern. During a productive stay in the realms of Atlantis, one might expect to find out how the Atlantians have solved the many challenges of life at the extremes.

Unlike Man, Atlantians have no borders, and may travel freely across the planet at will using their own bodies, albeit at low speed. To compensate for these limits, Atlantian ships are designed to resemble sea beasts, and follow the basic flow of sea currents. To accelerate, complex advancements in bubble cavitation and multiple oscillating thruster scilia, get around the factor traditionally thought of as “resistance”.

Much like the proposed Alcubierre hyperdrive would create a “bubble”, and using the same principle as that rescuing human Olympic divers from death when they plummet from incredible heights, disturbing the “surface” of the water, where it interfaces with the ship itself, means the resistance of water associated with surface tension, lessens remarkably. Bellows within the frame of the vessel perform peristalsis, pumping the ship through the oceans with shocking speed and unimaginable stealth to human means of detection.

The combination of borderlessness and rapid transport, means diplomacy is one of the most advanced technologies of Atlantis. The rapid declaration of an individual’s intent, needs and capacity when facing a stranger or opposing force has evolved into an art form, represented by marvellous bioluminescent displays and extremely complex scent patterns, each of which is shrouded in local cultural history and mystique too dense for this limited format. To humans, atlantian encounters are life-changing events, because of the extreme difficulties caused by a complete lack of lingua Franca. Between each other, Atlantians maintain strict social order and occasionally travel in pods, like cetaceans.

Chemistry and metallurgy are also specialties of the Atlantians. The presence of black smoker type oubierres into the Earths core, have spurred this development for millennia before the first human dried and burned peat, and discovered bloom in the ashes. Before the last ice age, approximately BCE15K Atlantians had already perfected complex alloys with exotic materials like manganese, molybdenum and chrome. This allowed them unimaginable advances in digging and burrowing, as the new materials could withstand heat better, and have cooling fluids pumped through the drill heads.

Forging is done by the aforementioned cavitation-technology, where repeated pulses of energy cause the material to heat up and deform. Within the burrowed and accidentally evacuated cavities of the Earth, the Atlantians discovered how to travel in extreme pressure dry environments. With mastery of both the dry and the wet, the Atlantians developed rapidly within the newly excavated, vast spaces below the seabed, and gradually developed towards independence from the surface oceans, in areas where the ice covered the northern hemisphere of Earth.


Mermaids would have an intuitive understanding of water currents, convection, and quite possibly sea life. Natural human curiosity and observation will likely lead to many animal-inspired technologies, selective breeding, and quite possibly pressure-related technology.

For example, an octopi's water jets (they use water for propulsion) could inspire pumps. Pufferfish could inspire something akin to our airbags. They could possibly discover metalworking, as ancient humans relied on 'native metals,' those that could be found in a relatively pure state: gold, silver, copper, tin, lead, and iron. If those can be found in such a state on land, then they might be found in that form underwater. And some of those metals (gold and lead, perhaps others) are easily worked, though that makes them bad for sturdy construction.

Until then, merpeople will be relying on stone (most likely fragments), coral, and animals/animal parts as weapons. Fire urchins could be flung (using seaweed slings) or swung (using seaweed rope tied, perhaps tightened, very carefully around the urchin). Octopus beaks, shark teeth, sharpened fishbones, and the like could work very well as weapons.

Since you specified mermaids, though, I see trouble on the horizon. That means they're all female, and to put it bluntly, women aren't natural fighters like men. Yes, they have a 'mama bear' instinct, but most women aren't fighters. It's perfectly feasible that your mermaids end up extremely primitive because: A) since they will likely be peaceful and avoid conflict (no need to make weapons if you don't want them or plan to use them) and B) Why build? Fish (and quite possibly mermaids, by extension) hide within, around, or underneath natural environmental structures (kelp forests, caves, coral reefs) and if shelter is relatively easy to come by, why would they develop engineering? Granted, rudimentary structures, like driftwood huts, are a possibility. But there's a good chance that they'll be nomadic. Think about it; do you see regular fish staying put in one area, or do you see them roaming about? C) No reason they'd have fire. Fire was important to human development, and since these mermaids will usually be underwater where fire doesn't exist (except, y'know, with underwater volcanoes) they'll avoid and fear fire, and intense heat in general. This seems an awful obstacle here, but hey! They'll be able to form gold jewelry, since it's so dang soft! (Seriously, it's the most malleable metal known to man.)

Finally, if these mermaids are anything like the stereotypical girl, they'll spend an awful lot of their time primping. However, primping serves one purpose; courtship display, really. This would explain why mermaids supposedly spend so much time singing or lounging about on rocks; they're trying to get a man! Since they're an all-female species, their survival literally depends on their success, and so technological advancement will likely be focused on cosmetics and flirting technigues.

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    $\begingroup$ -1, even if your assertions that females are less aggressive would hold for a non-human species, the use of weapons as tools for hunting and defense against predators cannot be understated. Similarly, engineering is a means to an end. Things like farming and transportation would be made easier by engineering. $\endgroup$
    – GOATNine
    Dec 26 '20 at 14:06
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    $\begingroup$ Good point, thank you for pointing that out. However, I did say it was _feasible_that they wouldn't be very advanced, not that they wouldn't be very advanced. $\endgroup$
    – Alendyias
    Dec 26 '20 at 20:42

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