Stock Photo - Caspian Sea, Mertvyy Kultuk Salt Flat, Kazakhstan August 1989. This west-looking view shows the northeast section of the Caspian Sea. The Caspian Sea is the world's largest inland expanse of water. The northern part of the sea visible in this view, reaches a depth of only 17 feet (5 meters). The Mertvyy Kultuk Salt Flat (bottom center) and the Kaydak Salt Flat (bottom left) are a part of the Caspian Depression and were once covered with water. The mouth of the Ural River is visible along the top of the image. The outer edges of the Volga River Delta are visible near the top center of the image. The area shown in this view is semi-arid, and is also noted for its many oil and gas fields.