Answer: Caspian Sea
Explanation:
The Caucasus mountain range is the highest in Russia, located between the Black Sea and the Caspian Sea, in the Caucasus region, between the basins of the Kuban River and the Térek River. This mountain range also has been considered the southeastern limit of Europe.
It should be noted that the highest point of this mountain range is Mount Elbrus (also the highest peak in Europe) with 5642 m of altitude. It is located in the western part of the Caucasian mountain range and, along with the Ural mountains, is the traditionally accepted border between Europe and Asia.