The Bosporus The Bosporus or Istanbul Strait is a body of water that separates the European and Asian sides of Turkey. It was named after the Greek legend of Io, a woman who was turned into a cow by Hera after she discovered that her husband Zeus had an affair with her. According to the legend, Hera created the horsefly to sting Io and remind her of her betrayal. The brooks that flow into the Bosporus were named "bous" because of their shape, which is said to resemble Io's form as a cow. Io spent part of her life on one side of the strait and the other part on the other side, until she finally found peace by crossing the strait once more. The Bosporus is the world's narrowest strait used for international navigation. It connects the Black Sea with the Sea of Marmara, which in turn connects to the Dardanelles and Aegean Seas, and ultimately to the Mediterranean via Greece. The strait is approximately 30 kilometers long, but its width varies between 700 and 3700 meters. The depth of the water ranges from 36 to 124 meters depending on the location. The city of Istanbul, the largest city in Turkey with over 16 million metropolitan inhabitants, is situated on the shores of the Bosporus. There are two bridges that cross the strait: the Bosphorus Bridge and the Fatih Sultan Mehmet Bridge (also known as the Bosphorus II).