I have a fantasy world with merfolk in it who have their own underwater civilization. While they are capable of trading and obtaining material from humans I want to figure out how much technology they could create on their own, using the natural resources around them. The time period the setting is based on is around 500 B.C. on earth.

I would want to know if my merfolk could accomplish making rope or weaving textiles on their own, because I think having something to tie other things with is very vital for most civilizations.

Kelp and animal tendons would be the obvious choices, and I think baskets and mats made of woven kelp would be very practical, but the material decay too fast due to being underwater to be useful for long?

  • $\begingroup$ Check this question for additional possible solutions. Leather nets could be used for the filters we discussed in another question. $\endgroup$
    – Otkin
    Aug 13, 2021 at 17:09
  • $\begingroup$ Also, take a look at sealskin leather and fish leather. The latter might not be suitable for ropes, but it should work for other things. Frequent oiling might be required, though. $\endgroup$
    – Otkin
    Aug 13, 2021 at 17:19

4 Answers 4


Their own hair.

Hair in the form of wool or other fibre has served as a natural resource to make cloths bedding and of course rope since time immemorial. Human hair has been used to great effect for rope-making, such as for the construction of The Higashi Hongan-ji Temple in Kyoto, Japan:

Great coil of hair rope in a display cabinet.

Erin Stevenson O'Connor, Creative commons Flickr via Atlasobscura.com 2021

The construction of the temple’s two main halls, the Founder’s Hall and the Amida Hall required the hoisting and moving of massive wooden beams, but unfortunately, obtaining rope strong enough for the job was nearly impossible at the time. Luckily, the female devotees of the temple got together to help out. Cutting off their long hair, they took the long locks and braided them together to make a strong, thick, gross rope that was able to hoist the heavy beams.

Since mermaids have always been so highly regarded for their beauty and their stunning hair (in their youth anyhow), perhaps at some point in their lives they sacrifice both, maybe with the coming of children, or marriage they cut off their hair to symbolize their devotion to family life (as opposed to sitting on rocks, stroking their hair and distracting sailors).

  • $\begingroup$ My merfolk generally don't have hair, and when they do its short and structurally more similar to catfish barbels or long filaments derived from scales. Long hair would be a very rare mutation so I don't know if hair could work. $\endgroup$ Aug 13, 2021 at 15:15
  • $\begingroup$ Does the fact that merfolk hair generally isnt very long and is more structurally similar to catfish barbels mean they cant use it as rope? $\endgroup$ Aug 16, 2021 at 9:31

Regular kelp may not work. But Bull Whip Kelp should prove sturdy enough and has a slow decay time. The kelp needs to be cured ( processed ) above water and on a slow flame. The resulting kelp can be twisted for added strength and used for everything from fishing lines to keeping objects on the floor of the water body, so nothing ( or no one ! ) floats to the top.

Since you mentioned you would rather avoid fire, you can use the hydrothermal vents which are relatively common on sea floors (and possibly very common in your fantasy world). These could be used in place of a fire, as they can reach temperatures well over 370C (700 F).

According to my search, curing kelp seems to be the same thing as drying it, so leaving it above water (on a beach or a raft) would complete this process faster.

One important note is bull whip kelp is an endangered species. So, unless your merfolk take care of the amount they harvest, you might want to steer clear of this option.

Good question, merfolk are always great to see in stories

  • $\begingroup$ Thanks for the answer! My merfolk live in a fantasy world so its possible theres a species similar to bullwhip kelp that isnt endangered. Curing it above water is doable if they find a small island/rock to place it on. But I dont think the merfolk could make fire on their own. However, I might just device a magical applied phlebotinium so they dont need fire, unless you have another solution for the lack of fire. $\endgroup$ Aug 12, 2021 at 21:38
  • $\begingroup$ Hmm, you can use hydrothermal vents at the sea floor which rise to temperatures of over 370C (~700F). Do you mind if the humans do the fire part? Or do you want the entire process to be done solely by merfolk ? (Updating the answer to include the vents) $\endgroup$ Aug 12, 2021 at 21:44
  • $\begingroup$ chemical secretion from some sea creature could be the curing agent. $\endgroup$
    – Allan
    Aug 12, 2021 at 21:57
  • $\begingroup$ The merfolk can seek humans to help with the fire part, but I'm interested in how much tech they could accomplish on their own. I think using the secretions of sea creatures as the curing agent works, but as for hydrothermal vents, I think it could work, the kelp being heated by being held above the vent at a safe distance, but would being cured and heated underwater be effective? $\endgroup$ Aug 12, 2021 at 22:10
  • $\begingroup$ I like the idea @Allan gave with the chemical secretions, though I do not know enough about it to elaborate. Leather can be cured in a variety of ways including wet-salting where leather is placed in a brine solution for a while. Another method could be leaving them to dry above water, under the sun. According to my search, curing kelp is similar, if not the same, as drying, so doing this above land would likely work faster. $\endgroup$ Aug 12, 2021 at 22:24

Posidonia oceanica can be an option

Posidonia oceanica is a flowering plant which lives in dense meadows or along channels in the sands of the Mediterranean. It is found at depths from 1–35 metres (3.3–114.8 ft), according to water clarity. Subsurface rhizomes and roots stabilize the plant while erect rhizomes and leaves reduce silt accumulation.

The leaves are ribbon-like, appearing in tufts of 6 or 7, and up to 1.5 metres (4.9 ft) long.

They already form fibrous balls, which can be found on the shores or many places. It would be an easy giveaway to start making ropes out of them.

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For thousands of years, people all over the world have been weaving seagrass. Some experts believe the use of seagrass in weaving objects could go back as far as 10,000 years.

Seagrass is exactly as the name implies, a grass that grows in the sea or in areas that have saltwater. As Vietnam has access to a lot of tropical oceans, seagrass is abundant in Vietnam. A lot of the seagrass used for manufacturing home decor products is farmed to be cut and processed specifically for seagrass weaving. This seagrass is cut, dried, spun, dyed, and then woven into many different items, including baskets, lampshades, furniture, and area rugs.

Seagrasses are common worldwide and there are several types. It is easy to find rope and woven materials made of seagrass for sale. Interestingly, though, the wikipedia articles on seagrasses make no mention of their commercial utility and instead are all about seagrass ecosystems, manatees etc. I suspect that what is being called "seagrass" for weaving and rope making purposes is actually rushes.

  • $\begingroup$ Does that mean that actual seagrass cant be used for ropemaking? $\endgroup$ Aug 13, 2021 at 16:07
  • $\begingroup$ @BoaHancocklover If you google "seagrass" I think the rope product you turn up are made with a rush. But the Smithsonian says that real seagrasses are used to make things. ocean.si.edu/ocean-life/plants-algae/seagrass-and-seagrass-beds My Googlefu is just not showing me exactly which species are used and how. $\endgroup$
    – Willk
    Aug 13, 2021 at 21:55

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