One of the worlds most strategic waterways, Bosphorus is the strait between the Black Sea and the Sea of Marmara; it is an inundated valley that follows an irregular northeast-southwest course 32 km (20 miles) long, 730-3300 meters (800-3600 yards) wide, 30-120 meters (100-395 feet) deep.
Bosphorus comes from a Tracian word of unknown origin, interpreted in Greek as meaning "Ford of the Cow", from the legend of Io, one of the many lovers of Zeus, who swam across the sea here as a cow chased and continuously disturbed by flies sent by Hera.
Known in Turkish as Bogazici (the Strait), it links the Black Sea with the Sea of Marmara and, with the Dardanelles Strait (in Canakkale), separates Europe from Asia. It is a former river valley which was drowned by the sea at the end of the Tertiary period. This is a very busy strait with many commercial ships and oil tankers, as well as local fishing and passenger boats.
The current flows from north to south; however, a strong subsurface countercurrent with numerous points and coves sets up swirls and eddies that make navigation dangerous to the inexperienced.
There are two suspension toll bridges over the Bosphorus Strait and the third one is being built.
- The first bridge is streching between Beylerbeyi neighbourhood on the Asişan side and Ortaköy neighbourhood on the European side. It was opened in 1973 and was called as "Bogazici (Bosphorus) Bridge", then in July 2016 it's named as "Martyrs of July 15th" dedicated to the victims died during the failed coup attemp of 15th of July 2016. It's 1074 meters (1175 yards) long, has 6 lanes, and 165 meters (540 feet) high piers.
- The second bridge streches between Anadolu Hisari and Rumeli Hisari. It was opened in 1988 and is called as "Fatih Sultan Mehmet Bridge" (abv. FSM). It's 1090 meters (1192 yards) long, has 8 lanes, 65 meters high from the water.
- The third bridge is under construction and is planned to be completed by the end of Summer 2016. It's located at the entrance from the Black Sea, streching between Garipçe village on the European side and Poyrazköy village on the Asian side. Its dimensions will be 1408 meters (1540 yards) long between two pillars, 59 meters (65 yards) wide with 8 lanes + 2 rail lines, and 320 meters (1050 feet) high pillars, one of the biggest suspension bridges in the world. It will be named as "Yavuz Sultan Selim Bridge".
There is also a tunnel under the Bosphorus, called Marmaray, which was opened in October 2013. This tunnel is for the subway system. Another tunnel is being constructed and planned to be completed by 2016. The second tunnel will be for the cars.
With the shores rising to heights up to 200 meters (650 feet), lined with palaces, ruins, villages, and gardens, this is one of the most beautiful stretches of scenery in Turkey. The best way of seeing the Bosphorus in all its beauty is to take a trip on one of the coastal boats, in this way you can also admire many of the old Ottoman wooden houses (called as Yali in Turkish). You can also stay in some of the best hotels or eat in some of the best restaurants along its shores during your stay in this magnificent city.
Some of the interesting palaces, buildings or neighborhoods along the Bosphorus are: Galata tower, Dolmabahce Palace, Ciragan Palace, Yildiz Palace, Besiktas, Ortaköy, Arnavutköy, Bebek, Rumeli Fortress, Tarabya, Yeniköy, Istinye, Sariyer, Uskudar, Kanlica, Beykoz, Anatolian Fortress, Beylerbeyi Palace and Kuleli Military High school.