Bosphorus is a natural strait connecting the Black Sea to the Sea of Marmara, thus being a very strategic waterway. It was a river in the valley during the Tertiary period of the continents, which was drowned by the sea at the end of this period. It's length is 32 kilometers (20 miles) in the north to south direction, width varies between 730-3300 meters (800-3600 yards), and depth is between 30-120 meters (100-395 feet). Bosphorus strait separates the European part from the Asian part of Istanbul. The surface current flows always from north to south; however, a strong countercurrent under the surface creates swirls and eddies.
Bosphorus comes from a Thracian word which means "passage of the cow", deriving from the legend of Io who was one of many lovers of Zeus. When Hera, Zeus' wife, suspected her husband being involved in a love affair with Io, Zeus converted Io in a small cow and tried to send her away from Hera's rage. She (the cow) swam across the strait but Hera discovered it and she sent big flies after the cow to bite and disturb her all the time, ending Io in the Aegean Sea (thus named Ionian sea).
Bosphorus in Turkish is known as Bogazici, meaning "inner strait". Since the ancient times it held always an important role because of its strategic location, being the only passage from the Black Sea into the Mediterranean, along with the Dardanelles strait. Especially during the Cold War, the straits were crucial for Soviet navy.
Bosphorus is a very busy waterway with many ships and oil tankers going through it, as well as local fishing and ferries go to the Asian side back and forth. Around 48.000 ships pass through this strait annually, three times denser than the Suez Canal traffic and four times denser than the Panama Canal. Approximately 55 million tones of oil are shipped through the strait each year.
There are two suspension bridges on the Bosphorus connecting Europe to Asia (or vice versa). The first one is known as "Bosphorus Bridge" and was opened on 29th October 1973 between Beylerbeyi and Ortakoy neighborhoods. It's 1074 meters (1175 yards) long between two pillars, has 6 lanes, 165 meters (540 feet) height of piers. The second one is known as "Fatih Sultan Mehmet Bridge" (or FSM Bridge shortly) and was opened in 3rd July 1988 between Anadolu Hisari and Rumeli Hisari neighborhoods. This one is 1090 meters (1192 yards) long, has 8 lanes, and is 65 meters high from the water surface. The FSM bridge is a part of TEM highway (Trans European Motorway) between Ankara and Edirne provinces. Both bridges are tolled which is paid during passage to Asian direction only. The first one accepts only vehicles with electronic pass system (called OGS) and the second one both OGS and cash. No bicycles nor pedestrian traffic is allowed on them. The construction of the third suspension bridge has started in May 2013 by a consortium of Italian and Turkish companies, planning to finish the construction by the end of 2015.
Today, a tunnel is in construction between Uskudar and Yenikapi neighborhoods. It's a big project sponsored and constructed by Japanese companies and will be open by the end of 2013, which is delayed for 4 years due to technical reasons and archaeological findings. This tunnel will connect only railways between Europe and Asia, not motor vehicles. Nowadays, there are plans to build another tunnel in the future which will serve to the cars.
Bosphorus is one of the most popular areas of Istanbul for its inhabitants, especially during Summer for its climate. Its shores are lined with fine neighborhoods, Ottoman palaces, fortresses, old wooden villas, hotels, parks and gardens, restaurants, cafeterias, and so on.
Some of the interesting neighborhoods on the Bosphorus are: Besiktas, Ortaköy, Arnavutköy, Bebek, Rumelihisar, Emirgan, Tarabya, Yeniköy, Istinye, Sariyer, Üsküdar, Kanlica, Beykoz, Anadoluhisar, Beylerbeyi, Cengelköy, and many others. Best way to see these sites would be taking a nice boat trip along the Bosphorus.
Click here for high resolution photo gallery of the Bosphorus.
Hope to see you soon in Istanbul.