Bosporus

The Bosporus (also spelled Bosphorus) is a natural strait in Turkey, with the city of Istanbul straddling both its banks. It connects the Black Sea to the Sea of Marmara and serves as one of the continental boundaries between Asia and Europe, while also dividing Turkey by separating Thrace from Asia Minor. It holds the distinction of being the narrowest strait in the world used for international shipping.

Most of the strait’s shores, except for the northern area, are densely settled. Istanbul’s metropolitan population of 17 million extends inland from both banks. The Bosporus, together with the Dardanelles Strait at the far end of the Sea of Marmara, is collectively known as the Turkish Straits. Sections of the Bosporus’s shore in Istanbul have been reinforced with concrete or rubble, and areas prone to deposition are periodically dredged.

The strait’s name comes from the Ancient Greek *Bosporos*, which was folk-etymologized as “cattle strait” (from *bos* meaning “ox” or “cattle” and *poros* meaning “passage”). This refers to the Greek myth of Io, who was turned into a cow and forced to wander until she crossed the Bosporus, where Prometheus comforted her, telling her she would be restored to human form and become the ancestor of Heracles. Io supposedly came ashore near Chrysopolis (modern Üsküdar), which was called “the Cow.” That site was also known as Damalis, after the Athenian general Chares erected a monument to his wife Damalis there, featuring a colossal statue of a cow (the name *Damalis* translates to “heifer”).

The English spelling with *-ph-* (Bosphor) is not supported by the ancient Greek name, and dictionaries prefer the *-p-* spelling. However, *-ph-* appears as a variant in medieval Latin (as *Bosphor*, *Bosphorus*, or *Bospherus*) and in medieval Greek (sometimes as *Bosphoros*), giving rise to the French *Bosphore*, Spanish *Bósforo*, Italian *Bosforo*, and Russian *Bosfor*. The 12th-century Greek scholar John Tzetzes called it *Damalietes* (after Damalis), but noted that in popular usage it was known as *Prosphorion*, the name of Constantinople’s oldest northern harbor. In English, the preferred spelling tends to be *Bosphorus*.

Historically, the Bosporus was also called the “Strait of Constantinople” or the Thracian Bosporus, to distinguish it from the Cimmerian Bosporus in Crimea. These names appear in Herodotus’s *Histories* (4.83) as *Bosporos Thrakios*, *Bosporos*, and *Bosporos Kimerios*. Other names Herodotus used include the Chalcedonian Bosporus and the Mysian Bosporus. The term eventually became a common noun meaning “a strait” and was applied to the Hellespont in Classical Greek by Aeschylus and Sophocles.

*Boğaziçi* refers to those parts of Istanbul and its administrative districts that have a view of the Bosporus. It particularly describes areas north of the Golden Horn (Haliç), starting with the European-side district of Beşiktaş. This includes, from south to north along the European shore: Beşiktaş, Ortaköy, Arnavutköy, Bebek, Rumelihisarı, Baltalimanı, Emirgan, İstinye, Yeniköy, Tarabya, Kireçburnu, Büyükdere, and Sarıyer. Along the Asian shore: Üsküdar, Beylerbeyi, Çengelköy, Vaniköy, Kandilli, Anadolu Hisarı, Kanlıca, and Beykoz.

There is one very small island in the Bosporus, just off Kuruçeşme. Now called Galatasaray Island (Galatasaray Adası), it was given to the Armenian architect Sarkis Balyan by Sultan Abdülhamid II in 1880. The house he built there was later demolished. The island became a walled garden, then a water sports center, before being given to the Galatasaray Sports Club, which gave it its name. In the 2010s, it was completely overbuilt with nightclubs, which the government tore down in 2017. It reopened exclusively to Galatasaray club members in the summer of 2022.

The exact cause and date of the Bosporus’s formation remain debated among geologists. One recent hypothesis, the Black Sea deluge hypothesis, launched by a 1997 study from two Columbia University scientists, suggests the Bosporus was flooded around 5600 BC.