The Caspian Sea is bounded by the Republic of Azerbaijan to the west.
Azerbaijan ( [ æzərbaɪˈʒɑːn ] ; Azərbaycan ) , officially the Republic of Azerbaijan ( Azərbaycan Respublikası ) , is a country in the South Caucasus region , situated at the crossroads of Southwest Asia and Southeastern Europe . Caspian Sea . It is bounded by Kazakhstan to the northeast , Russia to the northwest , Azerbaijan to the west , Iran to the south , and Turkmenistan to the southeast .