How the hell is the Caspian Sea brackish?

Great question — it's actually a fascinating geological story.
The Caspian Sea is landlocked, meaning it has no outlet to any ocean. Here's why that makes it brackish rather than either fully fresh or fully salty:
It used to be connected to the ocean. Millions of years ago, the Caspian was part of a vast ancient sea called the Paratethys, which was itself connected to the world ocean. As tectonic shifts raised the land around it, it got cut off — trapping ancient seawater inside.
Rivers dilute it constantly. The Volga River (and several others) dump enormous amounts of freshwater into it. With no outflow to the ocean, this freshwater just mixes with the trapped saltwater, diluting it over time. That's why it's only about one-third as salty as the ocean — roughly 1.2% salinity vs. the ocean's ~3.5%.
Evaporation concentrates what's left. Water evaporates from the surface, but the salt stays behind. So you have two competing forces: rivers constantly freshening it, and evaporation constantly concentrating whatever salt remains.
It's also uneven. The northern part (where the Volga empties) is nearly fresh, while the southern parts are saltier — so it's not even uniformly brackish throughout.
Essentially it's a relic of an ancient ocean that's been slowly freshening for millions of years but hasn't finished the job yet. Given enough time with no geological changes, the rivers would theoretically freshen it completely — but evaporation and residual salt keep it in this in-between state.

Same reason the Dead Sea is salty AF?

Yep yep. Take a pot of salty water and boil it. As water evaporates out, pour in more fresh water. As long as you keep the water level relatively stable, your salt to water ratio will remain relatively stable as well.

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How the hell is the Caspian Sea brackish?
That flow-in from the north you see is fresh water Volga River

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Two reasons.

1. Because there is a ton of leftover salt from when it was part of a much larger sea.

2. Because you touch yourself at night.

Aral sea (which the soviets detroyed) same story as Caspian

and sure enough, the smaller lakes around it, also with zero connect to any ocean, are also brackish


I wonder why no sharks were included in the ancient saltwater dump? Caspian Sea has no sharks, not even small ones.

You are talking salty, right?

I thought maybe you are Chinese and that would be different.

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Great Salt Lake?

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Yes, but how is Utah Lake, south of there maybe 40 miles, fresh water? It's a natural lake.

Why no salt there from the ancient dump of ocean water theory.

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aren't most sharks heavily migratory

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Depends on if they are African sharks or European sharks. African sharks are non-migratory.

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Certainly not my area of expertise, but aren't most sharks heavily migratory? I wonder if there was a population initially that died out due to disruption to their reproductive behaviors.

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Mine either obviously

but the Caspian is almost as big as the Black sea (which of course is connected to oceans) and the Black sea has small sharks.
Seems like small sharks would have had plenty of room to reproduce in the Caspian.