Ocean sourced Trade goods in a Renaissance era Earth

I am in the process of writing a fantasy book that is set in a post-apocalyptic late medieval/renaissance era society.
This is on Earth, about 1300-1500 years in the future following a complete societal collapse of decades.
A group of aquatic humanoids (I call them Delphians,) need to trade for metalwork goods, and I'm having difficulty finding trade goods that would be valuable to the land-dwellers that would be found in the ocean, other than seafood.
I've come across a few of them in my research that are available in today's society (regardless of legality or morality), such as:

  1. whale ivory
  2. mineral or metal nodules
  3. leather
  4. pearls (rarely, very druidic/harmonistic society underwater)

and possibly

  1. sea snails for the old fashioned purple dye

Thus far in the build, the aquatic humans are the only unusual biological presence other than a semi-intelligent parasite.
My question is, What sort of resources valuable to a Renaissance era society would come from the Continental shelf of the ocean?
Especially if it would be different from what is available or valuable in our modern era.

  • $\begingroup$ It really depends on what creatures exist in your post apocalyptic world, and as aquatic humans exist that implies an enormous potential for quite different creatures. $\endgroup$ Jul 17, 2020 at 13:50
  • $\begingroup$ Hadn't considered that when I wrote the question, Have edited it to show that there are not many differences in species to the modern era. Also this is definitely Earth, about 1300-1500 years in the future following a complete societal collapse of decades. $\endgroup$
    – DocBon3saw
    Jul 17, 2020 at 14:04
  • 2
    $\begingroup$ Byssus for making sea silk. Amber. Red coral. Sponges. Ambergris. (Funny thing, you'd have known about those things if only you had bothered to learn about sea resources exploited by ancient peoples...) $\endgroup$
    – AlexP
    Jul 17, 2020 at 14:41
  • 1
    $\begingroup$ @AlexP I bow to your superior google-fu. I did do some research, but somehow that had all escaped me. $\endgroup$
    – DocBon3saw
    Jul 17, 2020 at 14:49
  • 1
    $\begingroup$ oh yeah also cuttlefish and squid ink, its expensive as writing or painting ink and food delicacy, and if other location is ok, sea urchin, its quite fond by china in the past until its not. $\endgroup$
    – Li Jun
    Jul 17, 2020 at 15:13

4 Answers 4



These are great answers, and materially I can't compete with them. I see potential in labor as a marketable trade commodity. Humans have a long, complex relationship with the sea, and the labor of those who can move freely in it could be very valuable. My commercial ship sank? Hire a mer-crew to retrieve the goods. Want cold wine? I know a mer-guy with a deep hole where it gets cold.

What ocean voyage is safe without a mer-guide to escort you and smooth over potentially hostile relations? An angry mer-tribe will come and drill a hole in your ship if you tick them off, but with a guide to vouch for you, and possibly lubricate trade, your voyage becomes successful. They also know where the sandbars and clear channels are, and probably have ways of navigating the poor humans have no chance of competing with. Navigators were highly sought-after, but perhaps merfolk are SO good at it that no one uses them.

On the less scrupulous side of things, merfolk could be excellent mercenaries on the sea. What pirate wouldn't give all the crappy metal loot to merfolk in exchange for their help sacking ships? Jam the rudder on a merchant ship and good luck outdistancing pursuit. Alternately, jam the rudder of a pirate ship so the merchants can escape. This could even be a semi-acceptable protection racket. Well, haven't you noticed how bad the pirates are? I promise you will have no problems crossing this trade route for a modest fee.

  • 2
    $\begingroup$ better yet hire them to maintain ports and river ways, way faster and cheaper than dredges. ditto for scraping barnacles off ships. $\endgroup$
    – John
    Jul 18, 2020 at 0:16
  • $\begingroup$ @john It's a good point, I considered it. But they're druidic (might object to eco-damage) and dredging is very dirty work - not sure how functional they'd be in a polluted environment. $\endgroup$
    – DWKraus
    Jul 18, 2020 at 0:19
  • $\begingroup$ to be fair dredging is dirty becasue we pull it to the surface before moving it, it would be no dirtier than making their own buildings. but like I said ships maintenance, scouting fish, save sailors who fall overboard, drill holes in enemy ships, stack rocks to make harbor, ect. $\endgroup$
    – John
    Jul 18, 2020 at 0:32

Valuable dyes. In particular I am thinking of Tyrian purple sometimes called Phoenician purple.

This was a dye made from a particular sort of sea snail. They were gathered, mashed up, and the concoction was supposed to be the most foul-smelling thing imaginable in the ancient world (which is saying something, they weren't necessarily known for their hygiene). After fermenting for some set period of time, it could dye cloth a color that was impossible otherwise until the advent of aniline/synthetic dyes. What that color is, exactly, is unknown... I don't believe any examples survive.

Now, that doesn't mean that it's just "purple dye", or even "just a dye". Any number of strange biological substances could come from a sea. Pharmaceuticals (abortificients for instance) were difficult to come by, and could have almost any property that modern pharmaceuticals have.

Nearly anything that served the needs of your story could be chosen.

The only restrictions would be (if details were necessary) to tie it to an organism that lives in fairly shallow water (no more than about 40 meters deep), as they'd have trouble collecting it otherwise (fish can be caught at deeper depths, but are less plausible as the origin of interesting substances).

[edit] Didn't realize this question referred specifically to mermen. I retract the "shallow water" constraint. They can go just about anywhere to get the stuff, which may open up possibilities.


Relics of the sunken world.

enter image description here


The screenshot is from the movie Waterworld, where the merperson hero can visit the sunken cities and retrieve items. Mostly dirt, if I recall.

But in your post apocalyptic world, maybe the merpeople have access to sunken relics of the world that was. Their remoteness means they escaped looting in the centuries since the apocalypse and their deep locations means that the loot as escaped the travails of surface wind and weather.

The merpeople often do not know the significance or value of what they retrieve.

  • 2
    $\begingroup$ I imagine I'll be saying this a lot on this site, but I hadn't thought of this. Thank you. Upvote coming. $\endgroup$
    – DocBon3saw
    Jul 17, 2020 at 14:53
  • 1
    $\begingroup$ Just as an added side note: one should be mindful about taking that screenshot too literally. Even in a future where the polar ice caps were 100% melted away the Ocean would only rise about 60m. While many coastal towns would completely go under water, any buildings over 14 stories tall like those would have thier tops sticking out above the surface. $\endgroup$
    – Nosajimiki
    Jul 17, 2020 at 18:04
  • $\begingroup$ @Nosajimiki The ice caps melting aren't the only cause of oceans level rising due to global warming. Another is the expansion of the ocean water itself as it becomes warmer, just like the mercury or alcohol in a thermometer. When your thermometer is 4-5km deep, even a few degrees' difference can result in large changes in the surface level. $\endgroup$
    – Salda007
    Jul 18, 2020 at 2:40

Ambergris is used to create perfumes and is a very expensive commodity mainly because of its elusiveness. It is formed in the bowels of whales, perhaps they have discovered a way to farm whales for this resource?



You must log in to answer this question.

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