Lesbos or Lesvos is a Greek island located in the northeastern Aegean Sea. It has an area of 1,633 km2 (631 sq mi), with approximately 400 kilometres of coastline, making it the third largest island in Greece and the eighth largest in the Mediterranean. It is separated from Asia Minor by the narrow Mytilini Strait. On the southeastern coast is the island's capital and largest city, Mytilene (Μυτιλήνη), whose name is also used for the island as a whole. Lesbos is a separate regional unit with the seat in Mytilene, which is also the capital of the larger North Aegean region. The region includes the islands of Lesbos, Chios, Ikaria, Lemnos, and Samos. The total population of the island was 83,755 in 2021. A third of Lesbians live in the capital, while the remainder are concentrated in small towns and villages. The largest are Plomari, Kalloni, the Gera Villages, Agiassos, Eresos, and Molyvos.

The Aegean Sea is an elongated embayment of the Mediterranean Sea between Europe and Asia. It is located between the Balkans and Anatolia, and covers an area of some 215,000 km2 (83,000 sq mi). In the north, the Aegean is connected to the Marmara Sea, which in turn connects to the Black Sea, by the straits of the Dardanelles and the Bosphorus, respectively. The Aegean Islands are located within the sea and some bound it on its southern periphery, including Crete and Rhodes. The sea reaches a maximum depth of 2,639 m (8,658 ft) to the west of Karpathos. The Thracian Sea and the Sea of Crete are main subdivisions of the Aegean Sea.