The largest inland body of water in the world is the Caspian Sea. Despite its name, it is classified as a lake and is bordered by five countries: Russia, Kazakhstan, Azerbaijan, Iran, and Turkmenistan. The Caspian Sea has a diverse ecosystem and serves as an important resource for the surrounding nations, providing fish, oil, and natural gas. Its unique hydrology, saline composition, and varied habitats support numerous species, making it a crucial area for both ecological and economic activities in the region.