Caspian Sea is actually the world's biggest lake and not a sea

The Caspian Sea is the world’s largest inland water body enclosed or bordered by land on all sides. Going by the definition of a sea, the Caspian Sea is a lake and not a sea as it is an enclosed water body without any direct outlet to the ocean. However, 5.5 million years ago, it was part of the ancient Parathethys Sea and got landlocked due to tectonic uplift and sea-level fall. Hence, the seafloor of the Caspian Sea is composed of oceanic basalt and not continental granite.

Caspian Sea is actually the world's biggest lake and not a sea

Photo: www.worldatlas.com