Which strait separates Europe from Asia and flows through Istanbul?

The Bosphorus is the strait that separates Europe from Asia and flows through Istanbul.

It connects the Black Sea in the north with the Sea of Marmara in the south, forming part of the boundary between European Thrace and Asian Anatolia. Istanbul was built on both shores, making the waterway central to the city's geography and history.

The Bosphorus is about 30 kilometres long and is exceptionally narrow for an internationally navigable strait. Its currents generally flow southward at the surface, while a denser counter-current moves below. The name comes from an ancient Greek term often translated as “ox-ford.”

A common mix-up is the Dardanelles, another Turkish strait farther southwest. The Dardanelles connects the Sea of Marmara with the Aegean Sea, while the Bosphorus connects the Sea of Marmara with the Black Sea. Together, they are known as the Turkish Straits.