Bosporus

The Bosporus or Bosphorus, also known as the Istanbul Strait, (Turkish: İstanbul Boğazı) is a strait that forms the boundary between the European part (Rumelia) of Turkey and its Asian 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 (with a metropolitan area in excess of 11 million inhabitants) 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.

Formation of the Bosporus

The exact cause for the formation of the Bosporus remains the subject of vigorous debate among geologists. Thousands of years ago, the Black Sea became disconnected from the Aegean Sea. One recent theory (published in 1997 by William Ryan and Walter Pitman from Columbia University) contends that the Bosporus was formed about 5600 BCE when the rising waters of the Mediterranean/Sea of Marmara breached through to the Black Sea, which at the time (according to the theory) was a low-lying body of fresh water.

Some have argued that the resulting massive flooding of the inhabited and probably farmed northern shores of the Black Sea is thought to be the historic basis for the flood stories found in the Epic of Gilgamesh and in the Bible in Genesis, Chapters 6-9. On the other hand, there is also evidence for a flood of water going in the opposite direction, from the Black Sea into the Sea of Marmara around 7000 or 8000 BCE.

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 openly requested the concession of Soviet military bases on the Turkish Straits, even though Turkey was not involved in the war. This incident, coupled with Stalin's demands for the restitution of the Turkish provinces of Kars, Artvin and Ardahan to the Soviet Union (which were lost by Turkey with the Russo-Turkish War (1877-1878) but were regained with the Treaty of Kars in 1921) was one of the main reasons why Turkey decided to give up its principle of neutrality in foreign affairs and join NATO in 1952.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.

Sightseeing

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.