Flowing through the heart of Istanbul, in Turkey, the Bosphorus has been a flash point between cultures, religions and imperial powers for thousands of years; from the Roman and Byzantine Empires, to the clash between Islam and Christianity and the Cold War between the super powers of the East and West.
The Bosphorus has a rich and bloody history that's inspired poets, writers and artists from around the world.
Edward Stourton looks at that rich history and how the Bosphorus works today.
Fifty thousand vessels make their way through the narrow straits every year - everything from small fishing boats to giant oil and gas tankers battle through the treacherous currents - making it one of the busiest and most dangerous international waterways in the world.
(Image: People travel over the Bosphorus in a passenger-vehicle ferry in Istanbul. Credit: REUTERS/Murad Sezer)
Edward Stourton explores the history, religion and the mythology of the Bosphorus.