The Aegean Sea extends from the Mediterranean northward between Greece and Turkey. It covers an area of about 214,000 km² / 82,625 sq mi and surrounds many islands. Its southern entrance is partially blocked by the islands of Crete (Girit) and Rhodes (Rodos). The Aegean extends about 640 km / 400 mi from Crete northward to the coast of Thrace and its width ranges from 195-400 km / 120-250 mi.

The coast of the Aegean is mountainous and only in Macedonia and Thrace in the north are there extensive coastal plains. The narrow waterway known as the Dardanelles enters the Aegean from the northeast and carries the discharge from the Black Sea. It gives access through the Marmara Sea and the Bosphorus to the Black Sea. A major feature of the Aegean is that no ship can be out of sight of land for long. In classical times, this encouraged navigation and facilitated movement between its shores. Today most of the islands in the Aegean Sea are Greek.