The Caspian Sea is known as the largest inland lake in the world. Enclosed by the territories of five countries – Kazakhstan, Russia, Azerbaijan, Iran, and Turkmenistan – it covers approximately 371,000 square kilometers. Despite its name, the Caspian Sea is classified as a lake due to its lack of connection to the world's oceans. It is a vital resource for these nations, providing fisheries, oil, and natural gas. Its unique ecosystem is also a point of interest for researchers and environmentalists.