Two men in a boat travel on Sawa lake in Samawa, 270 km (160 miles) south of Baghdad February 21, 2013. One of the most well-known lakes in Iraq, Lake Sawa, is a large closed body of salt water situated in the desert between Baghdad and Basra. The lake is dubbed by some as "the Pearl of the South" for its beauty and unique composition. It is surrounded by a cliff of piled sand dunes, providing a natural levee that keeps the water above ground level. As the lake has no proven link to either river or sea, the source of its water has been a mystery to researchers for centuries. Picture taken February 21, 2013. REUTERS/Mohammed Ameen (IRAQ - Tags: ENVIRONMENT SOCIETY)