Symi, also transliterated as Syme or Simi, is a Greek island and municipality. It is mountainous and includes the harbor town of Symi and its adjacent upper town Ano Symi, as well as several smaller localities, beaches, and areas of significance in history and mythology. Symi is part of the Rhodes regional unit.
The economy of Symi was traditionally based on the shipbuilding and sponge industries. The population reached 22,500 at its peak during that period. Symi's main industry is now tourism, and its permanent population has declined to 2,500, with a larger population during the summer.
Geographically, Symi is part of the Dodecanese island chain, located about 41 kilometres (25 miles) north-northwest of Rhodes (and 425 km (264 mi) from Piraeus, the port of Athens), with 58.1 square kilometres (22.4 sq mi) of mountainous terrain. Its nearest land neighbors are the Datça and Bozburun peninsulas of Muğla Province in Turkey. Its interior is dotted with small valleys, and its coastline alternates between rocky cliffs and beaches, and isolated coves. Its main town, located on the northeast coast, is also named Symi and consists of the lower town around the harbour, typically referred to as Yialos, and the upper town is called Horio or Ano Symi.
In Greek mythology, Symi is reputed to be the birthplace of the Charites and to take its name from the nymph Syme (in antiquity the island was known as Aigli and Metapontis), though Pliny the Elder and some later writers claimed that the name was derived from scimmia "a monkey". In Homer's Iliad the island is mentioned as the domain of King Nireus, who fought in the Trojan War on the side of the Greeks. Thucydides writes that during the Peloponnesian War there was a Battle of Syme near the island in January, 411 BC, in which an unspecified number of Spartan ships defeated a squadron of Athenian vessels. Little was known about the island until the 14th century, but archaeological evidence indicates that it was continuously inhabited, and ruins of citadels suggest that it was an important location. It was first part of the Roman Empire and then the Byzantine Empire, until its conquest by the Knights of St. John in 1309.