Giant Inland Sea

Here is something I've been wanting to get people's thoughts on:

What could happen if a setting focused on a large inland sea? What I have in mind is a large sea covering the majority of a continent, but only ~20 feet deep at most and completely cut off from the ocean. What sorts of flora, fauna, geography, and cultures would be found in and around this sea? Below are a few of my thoughts, and I would love to hear anything else anyone has to contribute.

- Since the water is quite shallow, it allows for more varied and light-dependent life to exist. Think of the biodiversity of coral reefs, for example. Any animal which lives in the water is limited in size, although I'm not sure what the maximum size would be. A whale is probably out of the question, but could you have dolphins?

- Sea travel would probably be much less scary and dangerous. I believe shallower water would help limit the dangers of sailing, but boats would need to handle very shallow water fairly frequently, so they would be limited in size and type. (No giant cargo ships, for example. Probably more barge-like constructions.)

- Lots of water = lots of cultures and lots of interculture contact. I'm thinking of the Mediterranean here, because it's the largest semi-enclosed body of water currently. Lots of people trading and warring, ideas and materials going everywhere, and plenty of groups rising and falling from power. Sounds like ideal adventuring territory.

- At least one side of the sea would probably have pretty good rainfall, so there would be a lot of farming on that side, unless there were something preventing that. Beyond the rainfall the sea would provide, there's also everything that lives in the sea, so my guess is that food would be plentiful.

Those are some of the things I think would be likely in this kind of environment. What do you think?

Fully enclosed seas tend to vary in water level both season to season and over longer timescales (e.g. the Aral, Caspian seas.) As shallow as your sea would be that means significant changes in salinity, unless maybe it's fresh water all the time.

I suspect that some intelligent creatures would engage in dredging channels and reclaiming land for farming. There might be unintelligent creatures which build up their own structures (especially if the water's fresh), along the lines of beaver dams or anthills. The dolphin-equivalents would be troubled by both kinds but it was only recently that the Yangtze river dolphin went extinct so they can probably tolerate some.

Fortifications and borders inside the sea would be difficult; you could get a seagoing Khan or Napoleon conquering the whole thing in his lifetime. The Romans held most of the Mediterranean for a long time. Or a faster-growing people (in D&D worlds humans, orcs or goblins) expanding out over the top of slower-growing peoples. Are there powers which would stop this happening? You were wanting a diverse range of cultures here.

Are aquatic sentient races a part of this setting? A broad shallow sea would probably be ideal for merfolk and similar races - there would be lots of sea-bottom for them to engage in oyster farming and the like. You might even have aquatic races fighting over sea territory in a manner highly similar to the way dry-land peoples fight over land territory.

I'd go deeper than 20 feet -- that shallow, and you could see vast stretches of the thing completely dry in a bad drought year.


The effects of your inland sea will depend on surrounding geography and climate. I'd actually suggest looking at the effects of the Great Lakes of North America on the surrounding climate, growing regions, etc, if you're going to have a temperate land around this island sea. Lake effect snow is something many people haven't heard of, for example.

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Also see seagrass fields

Lots of aquaculture-seaweeds (nori), shellfish, seagrass (fiber),

Stellers Sea Cow-look it up-

Also - go deeper than 20 ft-say most is under 20 meters but with canyons and such deeper. And even those regions could have kelp forests.

Barges would be surprising common. Actually the tech of the ships may well be pretty low-seaworthyness not being a huge challenge.

Look at places like Holland, Haiphong Harbour boat people, Swamp Arabs, and Venice for ideas on how people live on shallow water.

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Originally Posted by sktarq

Also see seagrass fields

Lots of aquaculture-seaweeds (nori), shellfish, seagrass (fiber),

Stellers Sea Cow-look it up-

Also - go deeper than 20 ft-say most is under 20 meters but with canyons and such deeper. And even those regions could have kelp forests.

Barges would be surprising common. Actually the tech of the ships may well be pretty low-seaworthyness not being a huge challenge.

Look at places like Holland, Haiphong Harbour boat people, Swamp Arabs, and Venice for ideas on how people live on shallow water.

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I'd second looking at historical Marsh Arab culture (Mádan or Maida are others names used to denote this specific group); their mudhif buildings are especially impressive. They're large halls and houses made entirely from reeds, theyre really cool.

Swamps and wetlands are usually very good for growing rice, so rice or something similar would probably be great if the shallows of the sea aren't too salty (or you could use something like Morrowind's saltrice, which I always assumed was called that because they could grow it in the estuaries and tidal water in the Ascadian Isles and places like that).

Also, chinampas, built-up island gardens used by the Aztecs in Lake Texcoco to help feed Tenochtitlan, are cool historical ideas for food...maybe an island city in shallow sea surrounded by chinampas?

Coastal cities could be full of canals like Venice but the outskirts might be massive man-made orchard islands, you could have little shepherd islands like the Faroe and the Shetlands north of England, stilt house villages in the swamps, lots of water based trade, shallow water pirates, there's so many possibilities!!!!!

The first thing that popped into my head was the Black Sea. There you have a large, relatively isolated body of water with numerous cultures around the shoreline, and it's even big enough to have noticeable differences in climate from north to south.

I'm going to agree that it needs to be deeper than 20 feet. I would suggest just changing your units. Make it 20 fathoms at the deepest points. At that depth, there would be sections of the bottom that air breathers would have trouble reaching.

As for flora and fauna, probably mangrove and cypress trees near the shore. I doubt you would see beavers. They construct artificial ponds as a defense from terrestrial predators. This area would likely see more specialized aquatic predators. The shallows would be full of turtles, alligators, and even a platypus or two, while the deeper parts would hold sharks, dolphins, sturgeon, etc. If there are any small islands, they would probably serve as nurseries for seals and seabirds. I could definitely see large reefs, perhaps acting as a natural boundary between the "safe" shallows and the mysterious deep.

I kind of imagine a cluster of 1000 square foot "man made" islands all connected by stone bridges. The outer islands hold small groves of fruit trees and crop plots, while the middle islands hold large houses inhabited by the families farming the outer islands, and in the center is a square mile sized island holding a city. This city state is far out in the shallow sea, at least a hundred miles from any of the shores.

Just remember, any body of water that doesn't have an outlet will get saltier and saltier. Because the ocean is so vast it takes longer to see any changes.

Maybe if there is some kind of natural phenomenon that pulls the water towards some point and re-releases it out back into the inland sea? The Belgariad/Mallorian books had an endless maelstrom called the cherek bore, and the Odyssey had an eternal whirlpool called Charybdis (don’t' ever look to me for spelling) out in the Aegean sea. If there is something constantly pulling water gently towards itself, maybe the salt will be concentrated there? That could give the sea areas of varying salinity, with the areas near the shores being freshwater and the salt levels gradually growing as you approach the phenomenon to where at some point the water is like the ocean and the area around the phenomenon is like the dead sea

To follow up on my earlier post, a very shallow very large inland lake is in danger of becoming this, with just a very mild shift in climate. 20 feet is very likely to be seasonal, with fast stretches of the lake bottom exposed on a yearly basis.


Large, deep waters that stay open into the winter months of a temperate region can lead to lake effect snow. Parts of Michigan's Upper Peninsula average close to 250 inches of snow per year, and the record one-season snowfall east of the Rockies was set there.

Spoiler: That thing in front of the sign is a normal-size bench...

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https://upload.wikimedia.org/wikiped...hermometer.jpg

What if the lake was only land-locked for half of the year. Maybe spring snow melt causes the lake to rise dramatically allowing an outlet to form.

Okay, so the continent has ten major aquifers that form the sea, with the sea being their nexus. The maelstrom/whirlpool collects the salt, and evaporation keeps the sea from rising to the point where it forms a connection to the ocean. Maybe the sea is akin to the Florida everglades, only less grassy and sedgy.

The snowfall effect gives me an idea. A race of yetis that stay hidden in deep caves on the coast, and when the snow piles on, they wake from hibernation and go out hunting on the coast line killing all animals and sapient beings to stockpile meat to eat between snows.

Maybe giant tropical rivers flow in but the arctic outlet is frozen solid half the year meaning a seasonal current circles around. This keeps the salinity down but the river deltas are quite silty and opaque -- no coral reefs for miles out. Then you get a region like the Bahamas with clear water sunlit to the bottom. Then a great deep that sinks rather shallow compared to the ocean but the floor of the sea is beyond sunlight. Merfolk live on the slopes of the deep. They cultivate their own crops on the Sunbeds and are competing with men whose floating platforms and pearl farms interfere with the merfolk agriculture. On shore a mighty empire is trying to conquer the Known Coasts but the merfolk are starting to interfere with shipping across the great deep. The empire is seeking to build a ring of fortresses that are designed to fight men and merfolk. How that works remains to be seen. The kingdoms opposing the empire are not united but are coming to see the usefulness of alliance. Whether this can be worked out remains to be seen. There are rumors of sorcerors in the snowlands that seek to freeze the channel yearround to destroy the ecology of the sea. there are looser rumors of sea druids and witches who would oppose these magics with submarine artifacts of unknown power. The truth of these tales no man can yet say. The Thaw opens the sea to the Boatmen, coarse sea raiders in longboats. They have just been a nuisance but there are tales the Boatmen can conjure beasts from the ocean deeps to accompany them on their raids. None have yet been seen in the sea but who knows?