Kos or Cos is a Greek island, part of the Dodecanese island chain in the southeastern Aegean Sea. Kos is the third largest of the Dodecanese by area, after Rhodes and Karpathos; it has a population of 33,388 (2011 census), making it the second most populous of the Dodecanese, after Rhodes. Kos is in the Aegean Sea. Its coastline is 112 kilometres (70 miles) long and it extends from west to east.
In addition to the main town and port, also called Kos, the main villages of Kos island are Kardamena, Kefalos, Tingaki, Antimachia, Mastihari, Marmari and Pyli. Smaller ones are Zia, Zipari, Platani, Lagoudi and Asfendiou.