The Caspian Sea is next to the world's largest lagoon, according to Lakepedia. The 6,949-square-mile (18,000 square km) Kara-Bogaz Gol lagoon is on the eastern coast of the Caspian Sea and is separated from it by sand bars. A dam was built between the Caspian Sea and Kara-Bogaz Gol in 1980 but it was removed in 1992 because of the changes it caused to water levels.