Hydra, Greece

Hydra, or Ydra or Idra (Greek: Ύδρα, romanized: Ýdra, pronounced: [ˈiðra] in Modern Greek, Arvanitika: Nύδρα/Nidhra), is one of the Saronic Islands of Greece, located in the Aegean Sea between the Myrtoan Sea and the Argolic Gulf. It is separated from the Peloponnese by a narrow strip of water. In ancient times, the island was known as Hydrea (Ὑδρέα, derived from the Greek word for "water"), a reference to the natural springs on the island.

The municipality of Hydra consists of the islands Hydra (pop. 1,948, area 49.6 km² (19.2 sq mi)), Dokos (pop. 18, area 13.5 km² (5.2 sq mi)), and a few uninhabited islets, total area 64.443 km² (24.9 sq mi). The province of Hydra (Greek: Επαρχία Ύδρας) was one of the provinces of the Argolis and Corinthia prefecture from 1833 to 1942, Attica prefecture from 1942 to 1964, Piraeus prefecture from 1964 to 1972 and then back to Attica as part of the newly establishment Piraeus prefecture of Attica prefecture. Its territory corresponded with that of the current municipality. It was abolished in 2006. Today the municipality of Hydra is part of Islands regional unit of Attica region.