The Diocese of Odesa-Simferopol is a Latin Church ecclesiastical territory or diocese of the Catholic Church in southern Ukraine and Crimea. A significant part of the Latin Church in Ukraine, it covers an area equivalent to about one-third the size of Poland including areas impacted by annexation of Crimea by the Russian Federation, and the 2014 pro-Russian unrest in Ukraine. Since 2014, there has been a de facto inter-state border that splits the diocese.