Istanbul Visions - history, museums,monuments,shopping malls, culture and life,urban centers, religion and education in  Istanbul
Home Page | History | Museums | Monuments | Shopping Malls | Culture and Life | Urban Centers | Religion | Education | Links


The Bosporus (or Bosphorus), also known as the Istanbul Strait, is a strait that forms the boundary between the European part (Rumelia) of Turkey and its bosphorus in daytimeAsian part (Anatolia). The world's narrowest strait used for international navigation, it connects the Black Sea with the Sea of Marmara (which is connected by the Dardanelles to the Aegean Sea, and thereby to the Mediterranean Sea). It is approximately 30 km long, with a maximum width of 3,700 metres at the northern entrance, and a minimum width of 700 metres between Kandilli and Aşiyan; and 750 metres between Anadoluhisarı and Rumelihisarı. The depth varies from 36 to 124 metres in midstream. The shores of the strait are heavily populated as the city of Istanbul straddles it.

Two bridges cross the Bosporus. The first, the Bosphorus Bridge, is 1074 metres long and was completed in 1973. The second, Fatih Sultan Mehmet (Bosphorus II) bridge, is 1090 metres long, and was completed in 1988 about five kilometres north of the first bridge. A third road bridge is also being planned for one of seven locations designated by the Turkish Government. The location is being kept secret to avoid an early explosion in land prices. Another crossing, Marmaray, is a 13.7 kilometre-long rail tunnel currently under construction and expected to be completed in 2008. Approximately 1,400 metres of the tunnel will run under the strait, at a depth of about 55 metres.

On the surface, the Bosphorus flows like a river from the Black Sea to the Marmara. This current gets much stronger and becomes truly dangerous around the fortresses. Below the surface current, there is another current flowing in the opposite direction. These currents have always constituted a threat for the ships crossing the strait. The Bosphorus is like a narrow valley and it has an average depth of 50 and a maximum depth of 110 meters. Because of the currents and the different temperatures on various levels, the Bosphorus is a paradise for fish. The fish migrate between the Black Sea and the Marmara according to the season. These fish, peculiar to these waters, are caught during the migration seasons. Nowhere else can one find such fine-tasting fish. Until recent times, the settlements along the Bosphorus were quite limited due to the strong currents and the lack of roads. They consisted of a few villages, some imperial palaces and the mansions of the wealthy. In the 19th century the embassies started to build their summer residences here. Today the shores and the hills are developing as residential districts. There are numerous fish restaurants and cafes on both sides of the Bosphorus. Modern villas intermingle with the relatively few old wooden seaside mansions that have been preserved. One of the most beautiful sights in the world, the Bosphorus is a strait winding between two continents and joining two seas. The Black Sea is connected to the Aegean through the Bosphorus and the Dardanelles. It offers a different beauty each season, and in spring it is adorned with the pink flowers of the Judas trees.

The entrance to the Bosphorus is like a small bay, and from here one gets the best view of the old town. The rest of the 30 km long waterway is like a series of lakes. It is only from the air that one realizes it is a strait. The first bridge across the Bosphorus was completed in 1973, and the second, the Fatih (Mehmet the Conqueror) bridge in 1988. There are plans for building either a third bridge over or a tunnel under the strait. The settlements on the shore grew quickly after 1852 when steamboats were put into service here, and over time they became included in the city boundaries. The ancient name of "Bosphorus" means "Cow Passage". As a passage that can be traversed easily, it has facilitated the spread of civilizations between Asia and Europe and the development of trade and other relations. In the 2,500 year history of the city, the Bosphorus, its extension the Golden Horn and the historical peninsula have always been coveted places, and they witnessed numerous military campaigns and mass migrations. The earliest mention of the Bosphorus in mythology is in the story of the Argonauts who sail through the strait to the Black Sea. It is known that in 6th century BC the Persian armies tied their boats together for easier passage, thus forming the first bridge over the Bosphorus. Some of the noteworthy buildings on the European shore are the Ciragan Palace, which was restored and converted into a hotel, the former Feriye Police Station which is now used as a cultural center, and the Ortakoy Mosque and square. New five star hotels and tall buildings are springing up on the hills this side of the Bosphorus.

Ancient Greece, Rome, the Byzantines and the Ottoman Empire

As the narrowest point of passage between the Black Sea and the Mediterranean, the Bosporus has always been of great commercial and strategic importance. The Greek city-state of Athens in the 5th century BC, which was dependent on grain imports from Scythia, therefore maintained critical alliances with cities which controlled the straits, such as the Megarian colony Byzantium.bosphorus in  night

The strategic significance of the strait was one of the factors in the decision of the Roman Emperor Constantine the Great to found there in 330 AD his new capital, Constantinople, which came to be known as the capital of the Eastern Roman Empire. On May 29, 1453 it was conquered by the emerging Ottoman Empire. In fact, as the Ottoman Turks closed in on Constantinople, they constructed a fortification on each side of the strait, Anadoluhisarı (1393) and Rumelihisarı (1451). They later renamed the city Istanbul.

Strategic importance

The strategic importance of the Bosporus remains high, and control over it has been an objective of a number of hostilities in modern history, notably the Russo-Turkish War, 1877-1878, as well as of the attack of the Allied Powers on the Dardanelles in 1915 in the course of the First World War. Several international treaties have governed vessels using the waters, including the Montreux Convention Regarding the Regime of the Turkish Straits, signed in 1936. In the conferences during World War II, Soviet leader Josef Stalin demanded the deliver of the Bosporus to the USSR, even Turkey was not involved in the war. In more recent years, the Turkish Straits have become particularly important for the oil industry. Russian oil, from ports such as Novorossyisk, is exported by tankers to western Europe and the U.S. via the Bosphorus and the Dardanelles straits.


The cheapest way to experience Bosphorus in Istanbul would be to take one of the public ferries that travel between the Anatolian and Rumelian sides of the city. They depart every 45 minutes, and cost 1.3 YTL (about 0.80 Euros). There are also faster ferries that take off every 10 minutes, but the slower ones will give you more opportunity to see the city. One can also take a ride on a variety of tourist ships, from modern ones to Ottoman style ones. - 2007