Caspian Sea is large and heavily used for trade between adjacent countries, including Russia and Iran. This part of the world is somewhat unstable, and Russia is maintaining ability to intervene in case of an insurgency in the Middle Asia. I imagine that Caspian Sea is less significant for Iran than it is for Russia. read more
The Caspian Sea is the largest inland body of water in the world and accounts for 40 to 44% of the total lacustrine waters of the world. The coastlines of the Caspian are shared by Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan. read more