Antikythera (Αντικύθηρα, (ˌæntɪkɪˈθɪərə, an-ti-ki-theer-uh; , ahn-dee-kee-thee-rah)) is a Greek island community with a land area of 20.43 square kilometers, lying 38 kilometers south-east of Kythira. It is the most distant part of the Piraeus Prefecture from its heart in the Athens metropolitan area. It is lozenge-shaped, 10.5km NNW to SSE by 3.4km ENE to WSW. It is notable for being the location of the discovery of the Antikythera mechanism and for the historical Antikythera wreck.
Its main settlement and port is Potamós (pop. 18 inhabitants in 2001 census). The only other settlements are Galanianá (pop. 17), and Charchalianá (pop. 9). With only 44 inhabitants, it is the second-least populous community in Greece (after Gramos in Kastoria Prefecture). Antikythera is sporadically visited by the ANEN Lines ferry Myrtidossia, on its route between Piraeus (Athens) and Kissamos-Kastelli in Crete.
Between the 4th and 1st centuries BC, it was used as a base by a group of Cilician pirates until their destruction by Pompey the Great. Their fort can still be seen atop a cliff to the NE of the island.
Antikythera is most famous for being the location of the discovery of the Antikythera mechanism. The Antihythera mechanism is an ancient mechanical calculator (sometimes described as the first mechanical computer) designed to calculate astronomical positions which has been dated to about 150-100 BC. It was discovered in an ancient shipwreck off Antikythera in 1900. Technological artifacts of similar complexity did not appear until a thousand years later.
Antikythera is also a very important stop-over site for migratory birds during their seasonal movements, due to its geographical position and certain features (a longitudinal island, with a north-south direction and very low human activities). Furthermore the island hosts the largest breeding colony of Eleonora's Falcon (Falco eleonorae) in the word. The importance of Antikythira for studying bird migration led to the creation of Antikythera Bird Observatory (A.B.O) by the Hellenic Ornithological Society.