Kos or Cos is a Greek

Greece

Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

 island in the south Sporades

Sporades

The Sporades are an archipelago along the east coast of Greece, northeast of the island of Euboea, in the Aegean Sea. It consists of 24 islands, of which four are permanently inhabited: Alonnisos, Skiathos, Skopelos and Skyros.-Administration:...

 group of the Dodecanese

Dodecanese

The Dodecanese are a group of 12 larger plus 150 smaller Greek islands in the Aegean Sea, of which 26 are inhabited. Τhis island group generally defines the eastern limit of the Sea of Crete. They belong to the Southern Sporades island group...

, next to the Gulf of Gökova/Cos

Gulf of Gökova

Gulf of Gökova or Gulf of Kerme , is a long , narrow gulf of the Aegean Sea between Bodrum Peninsula and Datça Peninsula in south-west Turkey.Administratively, Gulf of Gökova coastline includes portions of the districts of, clockwise, Bodrum, Milas,...

. It measures 40 kilometres (24.9 mi) by 8 kilometres (5 mi), and is 4 kilometres (2.5 mi) from the coast of Bodrum

Bodrum

Bodrum is a port city in Muğla Province, in the southwestern Aegean Region of Turkey. It is located on the southern coast of Bodrum Peninsula, at a point that checks the entry into the Gulf of Gökova. The site was called Halicarnassus of Caria in ancient times and was famous for housing the...

, Turkey

Turkey

Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...

 and the ancient region of Caria

Caria

Caria was a region of western Anatolia extending along the coast from mid-Ionia south to Lycia and east to Phrygia. The Ionian and Dorian Greeks colonized the west of it and joined the Carian population in forming Greek-dominated states there...

. Administratively the island forms a separate municipality within the Kos peripheral unit

Kos (peripheral unit)

Kos is one of the regional units of Greece. It is part of the region of South Aegean. The regional unit covers the islands of Kos, Nisyros and several smaller islands in the Aegean Sea.-Administration:...

, which is part of the South Aegean Periphery

Peripheries of Greece

The current official regional administrative divisions of Greece were instituted in 1987. Although best translated into English as "regions", the transcription peripheries is sometimes used, perhaps to distinguish them from the traditional regions which they replaced. The English word 'periphery'...

. The principal town of the island and seat of the municipality is Kos town.