The largest lake in the world by surface area is the Caspian Sea, located between Europe and Asia. It covers approximately 371,000 square kilometers (143,000 square miles), making it not only the largest lake but also the largest enclosed inland body of water on the planet. Despite being called a "sea," it is classified as a lake due to its lack of connection to the world's oceans. The Caspian Sea is bordered by five countries: Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan. It has diverse ecosystems and is known for its rich natural resources, including oil and gas.