I get the Caspian Sea and the Black Sea a bit mixed up

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They are almost right next to each other, but they are separate.
I find them a bit confusing.
To be honest, rather than being categorized as seas, they both seem more like lakes.
Both likely have less water volume than Lake Baikal.
Actually, even Lake Baikal was referred to as a sea in ancient texts. It's famous because Huo Qubing advanced at a ghost-like speed right up to that point...