The Sea of Marmara, a northeastern extension of the Mediterranean Sea, separates Asian Turkey from European Turkey (Trace), thus it separates the two continents.
Bordered completely by Turkey, it connects to the Aegean Sea via the Dardanelles Strait, and to the Black Sea through the Bosporus Strait.
This (somewhat salty) body of water serves as a primary highway for the transport of energy to Europe from Russia and western Asia. In 2005 over 55,000 ships, including almost 6,000 oil tankers passed through it, most carrying Russian oil.
It contains two island groups; the Marmara in the southwest and the Princes' in the northeast. On the small island of Imrali stands a maximum-security prison that holds just a few prisoners, including Abdullah Ocalan, the leader of PKK, a Kurdish terrorist group.