1. Mykonos, Greece The island has an area of 85.5 square kilometres (33.0 sq mi) and rises to an elevation of 341 metres (1,119 feet) at its highest point. It is situated 150 kilometres (93 miles) east of Athens in the Aegean Sea. The island features no rivers, but numerous seasonal streams two of which have been converted into reservoirs. The island is composed mostly of granite and the terrain is very rocky with many areas eroded by the strong winds. High quality clay and baryte , which is a mineral used as a lubricant in oil drilling, were mined on the eastern side of Mykonos until the late 1900s. It produces 4,500 cubic metres (160,000 cu ft) of water daily, by reverse osmosis of sea water in order to help meet the needs of its population and visitors. [15] The island has a population of nearly 12,500, most of whom live in the main town of Chora . [16]