Oil was discovered in the Caspian Sea off the coast of Azerbaijan, leading to the construction of Neft Daşları, the world's first offshore oil platform.

The Caspian Sea is the world's largest inland body of water, also described as the world's largest lake and usually referred to as a full-fledged sea. An endorheic basin, it is situated in both Europe and Asia: east of the Caucasus, west of the broad steppe of Central Asia, south of the fertile plains of Southern Russia in Eastern Europe, and north of the mountainous Iranian Plateau. It covers a surface area of 371,000 km² (143,244 sq mi), an area similar to Japan, with a volume of 78,200 km³ (19,000 cu mi). It has a salinity of approximately 1.2%, about a third of the salinity of average seawater. It is bounded by Kazakhstan to the northeast, Russia to the northwest, Azerbaijan to the southwest, Iran to the south, and Turkmenistan to the southeast. The name of the Caspian Sea is derived from the ancient Iranic Caspi people.