The Sea of Marmara /ˈmɑrmərə/ (Greek: Θάλασσα του Μαρμαρά, Turkish: Marmara Denizi), also known as the Sea of Marmora or the Marmara Sea, and in the context of classical antiquity as the Propontis (Greek: Προποντίς), is the inland sea that connects the Black Sea to the Aegean Sea, thus separating Turkey's Asian and European parts. The Bosphorus strait connects it to the Black Sea and the Dardanelles strait to the Aegean. The former also separates Istanbul into its Asian and European sides. The Sea has an area of 11,350 km² (280 km x 80 km) with the greatest depth reaching 1,370 m.
https://en.wikipedia.org/wiki/Sea_of_Marmara