Serifos is a Greek island municipality in the Aegean Sea, located in the western Cyclades, south of Kythnos and northwest of Sifnos. It is part of the Milos regional unit. The area is 75.207 km² and the population was 1,414 at the 2001 census. It is located about 170 km (92 nmi) ESE of Piraeus. When Acrisius was warned by an oracle that his own grandson would kill him, he cast his daughter and her infant son Perseus adrift at sea in a wooden chest. It was the island of Serifos where the vessel had come ashore.