eli5 why is the caspian sea considered a sea and not a lake?

34 views

I mean it’s completely land locked why isn’t it considered a lake?

In: 2

Because of its salinity.

Fresh water is defined as anything with less than 1000 ppm of salt, while the Caspian Sea has 12800 ppm on average, and regular ocean water about 35000 ppm.

Sources:

* [https://www.usgs.gov/special-topics/water-science-school/science/saline-water-and-salinity](https://www.usgs.gov/special-topics/water-science-school/science/saline-water-and-salinity)
* [https://www.britannica.com/place/Caspian-Sea](https://www.britannica.com/place/Caspian-Sea)

Because lakes have a drain that ultimately leads to an Ocean. E.g. Lake Superior (one of the largest lakes in the world) drains through several rivers and lakes, which ultimately lead to the Atlantic Ocean.

The Caspian Sea has no such drain, the water doesn’t flow anywhere else. The Caspian Sea mostly loses water through evaporation, which steadily increases its salinity.

If we want to be technical, it should be considered an ocean because it has no outflows. Although by that logic, the Dead Sea, Lake Chad, and Great Salt Lake are also oceans.

But the people who first called it a “sea” didn’t know any of that. They just called it a “sea” because its a huge body of salt water.