Marmara Ereğlisi, also spelled Marmaraereğlisi, is a municipality and district of Tekirdağ Province, Turkey. Its area is 175 km2, and its population is 29,549 (2022). The mayor, as of September 2023, is Hikmet Ata (AKP).

The Sea of Marmara, also known as the Sea of Marmora or the Marmara Sea, is a small inland sea located entirely within the borders of Turkey. It connects the Black Sea to the Aegean Sea via the Bosporus and Dardanelles straits, separating Turkey’s European and Asian sides. It has an area of 11,350 km2 (4,380 sq mi), and its dimensions are 280 km × 80 km. Its greatest depth is 1,370 m (4,490 ft).