Did you know that the Caspian Sea, the saltwater lake in southeastern Europe and southwestern Asia, the largest inland body of water in the world is located in this part of the world? The Caspian Sea is bordered on the west by Azerbaijan and Russia and on the south by Iran. If you travel to the northern part of Iran, to Gilan or Mazandaran, you will explore this beautiful part of the world. The southern and southwestern shorelines of the Caspian Sea are bordered by the Elburz Mountains.