Thasos or Thassos is a Greek island in the North Aegean Sea. It is the northernmost major Greek island, and 12th largest by area. The island has an area of 380 km² and a population of about 13,000. It forms a separate regional unit within the East Macedonia and Thrace region. Before the local administration reform of 2011, it was part of the Kavala Prefectu…Thasos or Thassos is a Greek island in the North Aegean Sea. It is the northernmost major Greek island, and 12th largest by area. The island has an area of 380 km² and a population of about 13,000. It forms a separate regional unit within the East Macedonia and Thrace region. Before the local administration reform of 2011, it was part of the Kavala Prefecture. The largest town and the capital is Thasos, officially known as Limenas Thasou, "Port of Thasos", situated on the northern side. It is connected with the mainland by regular ferry lines between Keramoti and Thasos town, and between the regional centre of Kavala and Skala Prinou.