What strait connects the Black Sea to the Sea of Marmara?

The strait connecting the Black Sea to the Sea of Marmara is the Bosphorus.

Also spelled Bosporus, it is a natural waterway running through Turkey and dividing Istanbul between its European and Asian sides. From the Sea of Marmara, ships can continue through the Dardanelles into the Aegean Sea and then the wider Mediterranean.

The Bosphorus is one of the world’s most strategically important waterways. It provides the maritime route linking Black Sea ports in countries such as Turkey, Ukraine, Russia, Georgia, Romania, and Bulgaria with global shipping lanes. The Montreux Convention governs passage by certain military vessels and gives Turkey significant authority over the strait.

A frequent mix-up is the Dardanelles: the Dardanelles connects the Sea of Marmara to the Aegean, while the Bosphorus connects the Black Sea to the Sea of Marmara. Together, these waterways are known as the Turkish Straits. “Bosphorus” comes from an ancient Greek name often interpreted as “ox-ford.”