Spetses (Modern Greek: Σπέτσες, Katharevousa: Σπέτσαι, Spetsai, Ancient: Πιτυούσσα, "Pityoussa") is an island and a municipality in the Islands regional unit, Attica, Greece. It is sometimes included as one of the Saronic Islands. Until 1948, it was part of the old prefecture of Argolidocorinthia, which is now split into Argolis and Corinthia. In ancient times, it was known as Pityoussa, and later as Petses. The town of Spetses (pop. 3,846 in 2001) is the only large settlement on the island. The island is presently an independent municipality (pop. 3,916), with no internal boundaries within the municipality. The other settlements on the island are Moní Agíon Pánton (pop. 32), Ligonéri (16), Ágioi Anárgyroi (11), Kouzoúnos (3). Also part of the Municipality of Spetses are the islands of Spetsopoula (pop. 11) and Velopoula (uninhabited).
Ferries and high-speed hydrofoils arrive regularly from Piraeus. The new port is known as Dapia and the old port as Baltizar. Trails encircle the island and total about 25 to 30 km; beaches include Agios Mamas, in the center of town, Agioi Anargiroi and Agia Paraskevi at the back of the island, Zogeria, and two beaches close to the town, College beach and Agia Marina, both of which offer watersports.