a group of 77 islands and numerous cliffs in the Aegean Sea; part of Greece. Area, 540 sq km. The largest islands are Skiros, Skopelos, Skiathos, and Iliodhromia. Elevations range from 500 to 793 m. The islands are composed primarily of limestones, and have karst topography. Thickets of maquis grow on the islands. The inhabitants engage in subtropical farming, cattle breeding, and fishing; sponges are also harvested.