Istanbul's districts extend far from the city center along the full length of the Bosphorus (with the Black Sea at top and the Sea of Marmara at bottom).
NO !
This city is Istanbul but the city-proper is not so close to the Black Sea. (The Istanbul metropolitan area nearly extends to the Black Sea.)
The Bosporus Strait in Istanbul is usually considered the entrance to the Black Sea.
Bosphorus ( Boğaziçi in Turkish) seperates European istanbul from Asian Istanbul. Istanbul is surrounded with Black Sea at the north and Marmara Sea at the south. Here Bosphorus is the sea flow of these two seas.
the black sea
The Bosporus Strait, the Black Sea, and the Sea of Marmara surround Constantinople or Istanbul.
Istanbul
Istanbul is located on the Bosporus Strait.
Istanbul
Its location at the being of the Black Sea has made Istanbul a trading center
This is Istanbul, located on the coast of Marmara Sea. The entire peninsula of Anatolia splits the Black Sea and the Mediterranean Sea, so any city on the Anatolian peninsula is located between the Black Sea and Mediterranean Sea, including: Istanbul, Bursa, Izmir, Bodrum, Marmaris, Antalya, Ankara, Samsun, Eskişehir, Konya, Kayseri, and Adana, just to name a few.