The Bosphorus is the narrow strait between the Black Sea and the Sea of Marmara. The ortigin of the name is not known, but the Greeks interpreted it as “the cow’s ford”. According to an old Greek legend, it was the place where Io, who had been changed into a cow by her lover Zeus to hide her from the supreme god’s jealeous wife Hero, crossed from Europe to Asia.
Because the north-south current is extremely fast and the winds are predominantly from the north, it is very difficult to move from the Sea of Marmara to the Black Sea. This is why Byzantium, situated on the southern entrance, became an important town: sailors had to go ashore and rest before they could start rowing up north.