|Area||13.537 km2 (5.227 sq mi)|
|Pop. density||1.3/km2 (3.4/sq mi)|
Dokos (Greek: ) is a small Greek island of the Argo-Saronic Gulf, adjacent to Hydra, and separated from the Peloponnese by a narrow strait called, on some maps, "the Hydra Gulf." It is part of the municipality of Ýdra (Hydra) in Islands regional unit and reported a population of 18 persons at the 2011 census. The island is populated only by some Orthodox monks and perennial sheep herders. The island is rocky, reaching a height of 308 metres. During the ancient times it was called Aperopia ().
It has, since the ancient years, considered to be a strategic location. On the east side lie the ruins of a great Byzantine - Venetian Castle. During the Middle Ages, the island served as a refuge for Albanian settlers' animals.
Dokos, according to archaeological studies, has been inhabited since Chalcolithic, 6000 BC. In 1975, Peter Throckmorton discovered a wreck near Dokos that has been dated to about 2150 BC, and may be the oldest shipwreck known.