Bosporus

The Bosporus is a natural strait in northwestern Turkey that connects the Black Sea to the Sea of Marmara and forms the boundary between Europe and Asia. It runs through Istanbul, separating the city into its European and Asian parts, and is one of the world’s most important waterways for international shipping, naval passage, and passenger ferries.

The strait is about 29 kilometers long. Its narrowest point is roughly 700 meters across, with wider sections opening into the Sea of Marmara. Water depth and currents vary along its length, and the strait supports a high volume of vessel traffic, including large commercial ships and tankers, as well as domestic and international ferries.

Turkey exercises sovereignty over the strait, and its navigation regime is shaped by the Montreux Convention of 1936, which governs passage of ships during peacetime and wartime, including limits on military tonnage and duration for non-Black Sea states. The Bosporus remains a strategic point in regional security and global trade.

Infrastructure on and around the strait includes several major crossings. The Bosphorus Bridge, officially named the 15 July Martyrs Bridge, opened in 1973. The Fatih Sultan Mehmet Bridge followed in 1988, and a third crossing, the Yavuz Sultan Selim Bridge, opened in 2016 as part of the Northern Marmara Motorway. The Marmaray project, opened in 2013, provides an undersea rail link between the European and Asian sides. In addition, numerous ferries operate across the strait, linking communities on both shores.

Etymology: The name Bosporus derives from ancient Greek Bosporos, from boús “cow” and poros “ford,” reflecting an old toponym for the crossing. The strait has been a major conduit of trade and culture since antiquity.