Serifos is a Greek island situated in the Aegean Sea within the western Cyclades archipelago. It is positioned south of Kythnos and northwest of Sifnos, falling under the jurisdiction of the Milos regional unit. The island is located approximately 170 kilometres east-southeast of the port of Piraeus in Athens.
The land area of Serifos covers 75.207 square kilometres (29.038 sq mi). According to the 2021 census, the island had a population of 1,241 residents.