The Bosphorus runs about 30 kilometres from the Sea of Marmara to the Black Sea, dividing Istanbul between Europe and Asia and narrowing to about 700 metres between two old fortresses. From a deck the shore reads as one line: the marble front of Dolmabahçe Palace at Beşiktaş, wooden yalı houses at the water's edge, and Rumeli Hisarı, the fortress Mehmed II built in 1452 to control the strait.

Three bridges cross overhead, from the 1973 span at Ortaköy to the newest far north. A shared cruise leaves on a timetable from Eminönü or Kabataş, holds to a fixed route and sells single seats; the ferry version runs to Anadolu Kavağı and fills a day. A private yacht is hired by the hour from a marina such as Kuruçeşme or Bebek, crew included, and you choose the turning point. Two hours covers the second bridge and back; four or more are needed for the Black Sea mouth or the Princes Islands, where cars are banned.

May to October is the comfortable season. Boats work all year, but winter sailings can be cancelled for fog or wind, and from November a heated saloon matters. Evening trips are timed to sunset: after 20:00 in June, before 17:00 in December. Charter is priced per hour with a two-hour minimum, and the rate usually covers fuel, crew and mooring; food and drink are extra, though catering can be brought aboard. Nobody swims: this is a working shipping lane with a strong current. Confirm the boarding marina, and ask whether a weather cancellation means a new date or a refund.