Sea of Marmara, Turkey August 1997 The small inland Sea of Marmara (The Sea of Marble), between the European (bottom) Turkey and Asiatic (upper) Turkey, can be seen in this south-southwest-looking view. The sea is 170 miles (275 km) long and 50 miles (80 km) at its maximum width. The Sea of Marmara covers an area of 4,300 square miles (11,800 square km). Its maximum depth is about 4,500 feet (1370 meters) and there are no strong currents. The tidal range is minimum. The Sea of Marmara is a strategically important sea route for the shipping fleets of the world that travel between the Black Sea and the Mediterranean Sea. Numerous islands are situated in the Sea of Marmara, including the island of Marmara (lower right quadrant) where marble and alabaster are quarried.