Travel-World Photography
Bosporus Strait, which is also called The Golden Horn, connects the Mediterranean with the Black Sea. As the latter is also International waters, the shipping is free to travel the Strait. And the shipping is heavy through the minimum with of only 700 m. The Strait is about 30 km long, but is relatively deep, at 110 m at the most.
One hypothesis is that the Mediterranean sea flowed into and created the Black Sea around 7500 years ago. This was due to the land rise after the latest Ice Age. However, that theory is disputed.
Istanbul City is straddling the Strait, and a number of local ferries cross every day. East of the city center, the Bosporus Bridge was completed in 1973, and has a free span of 1074 m.