Three sides of Turkey are surrounded by seas. The three seas out of the four: Black Sea, Aegean Sea and Mediterranean Sea open to Atlantic Ocean. Marmara Sea, connecting Black Sea to Mediterranean is located inside the borders of Turkey.

Turkey's Seas

Black Sea: Having an aspect of a surrounded sea, the total length of the shores of Black Sea is 1695 Kilometers, the deepest point is 2244 meters, and the surface area is 424.000 Km2.
Average Salinity Ratio: 18 %, at the river entrances: 15 - 16 %.

Marmara Sea:
Marmara Sea is a small inner sea between Black Sea and Mediterranean Sea. The length of the shores is 1189 Km, and the depth is 760 m-3500 m. Marmara Sea connects Black Sea and Mediterranean Sea to each other.
Average Salinity Ratio: 26 %

Aegean Sea:
Aegean Sea is the sea having the longest and most crowded shores of Turkey. The length of the shoreline is 2805 km, and the deepest point is 1000 m.
Average Salinity Ratio: 38 % in North, 39 % in South

Mediterranean Sea:
It is the eastern part of actual Mediterranean Sea located at the southern part of Turkey. The length of the shoreline is 1577 Km; the surface area is 2.890.000 km2.
Average Salinity Ratio: 39 %