Vouliagmeni (Greek: Βουλιαγμένη, meaning "sunken") is a seaside suburb and former municipality 20 km south of Piraeus city centre. Since the 2011 local government reform it is part of the municipality Vari-Voula-Vouliagmeni, of which it is a municipal unit. The municipal unit has an area of 5.805 km2.
Its population was 4,180 at the 2011 census. In 1993 and again in 2009, it hosted the annual meeting of the Bilderberg Group.
The suburb is named after Lake Vouliagmeni, located in its vicinity. It is one of the most prestigious Athenian suburbs, home to renowned hotels and beaches. The area has some of the highest real estate prices in the Balkans.
Ruins of the Temple of Apollo Zoster have been excavated and can be viewed inside the public Astir Hotel beach. According to legend, when Leto was about to give birth to Apollo and Artemis, she fled writhing in pain to Delos. During her flight she discarded her girdle, which fell on the Mikro Kavouri peninsula. When her son, the god Apollo, was born, he picked up the discarded girdle and girdled himself in honour of his mother, and was hence named "Zoster" (Girt). Other remnants of early human habitation found in Vouliagmeni include Neolithic and Bronze Age building foundations, and a 5th-century BC outpost. In classical times the area was the Athenian deme of Aixōnídes Halaí (Greek: Αἰξωνίδες Ἁλαί), i.e. the Saltfields of Aixōnē (modern day Glyfada). The deme's citizens were called Ἁλαεῖς, Halaeīs.