This sea is really a lake. black caspian dead mediterranean.

ANSWER:

The Caspian Sea is a lake and not a sea in the true sense.

EXPLANATION:

This is because there is no inlet that leads from an ocean into the Caspian Sea. Caspian Sea is the "largest salt water lake" in the world. It was considered a sea because it was very large and also salty and ancient people therefore called it a sea. However, because the Caspian Sea does not connect to an ocean in any manner, it is a lake. The Caspian Sea also does not have an outlet to the ocean but because of its large size, it is called a sea.