Vouliagmeni sits on the southwestern foot of the Hymettus mountain range, 18 kilometres south of central Athens, where the city finally runs out of road and the Saronic Gulf takes over. The main boulevard, Athinas Avenue, runs parallel to the shore, lined with palms, with the rocky hillside of Hymettus rising to the east and the sea to the west. Between the road and the water, pine trees cover two small peninsulas known as Megalo Kavouri and Mikro Kavouri — the Big Crab and the Little Crab — with sandy and pebble beaches between them, luxury hotels along the waterfront (including the Astir Palace Hotel, which occupies most of Mikro Kavouri), two marinas, and restaurants facing the sea. The Vouliagmeni beaches consistently earn EU Blue Flag certification for environmental quality. Mikro Kavouri connects to the mainland by a narrow sandy isthmus called Laimos — the Neck — with a public beach on one side and the Astir Palace beach on the other. The two Kavouri peninsulas, dotted with villas, hold some of the most expensive residential real estate in Greece.

The land has been inhabited for a very long time. Neolithic and Bronze Age building foundations have been found here, along with a 5th-century BC outpost. In classical times the area was the Athenian deme of Aixonides Halai — the Saltfields of Aixone. And on the beach inside what is now the Astir Hotel property, the excavated ruins of the Temple of Apollo Zoster can be viewed. The name Zoster means "girdled," and the myth attached to the place explains it: when Leto, pregnant with Apollo and Artemis, was fleeing in pain toward Delos, she discarded her girdle on the Mikro Kavouri peninsula. When Apollo was born, he retrieved it and wore it in his mother's honour, earning the epithet Zoster. The story may be fanciful, but the ruins are real. A god's lost girdle, turned to stone on a beach where people still swim.

Lake Vouliagmeni is a geological rarity. It is a brackish lake — part fresh, part salt — fed not by any river but by underground currents filtering through the limestone of Mount Hymettus and mixing with seawater that has seeped through the coastal rock. The comfortable year-round temperature, between 22 and 29 degrees Celsius, has made it a natural spa for as long as people have been here. The water is clear, the surrounding cliffs dramatic, and the combination of warmth and geological strangeness attracts both local swimmers and visitors throughout the year. The suburb is named for the lake; the lake is named for the geological event that formed it. Everything else in Vouliagmeni radiates outward from that original sinking of the land.

The Nautical Club of Vouliagmeni, founded in 1937, operates from the eastern edge of Mikro Kavouri and has produced a remarkable tradition in water polo: both the women's and men's teams have won multiple Greek and European championships, and the club regularly fields players for the Greek national teams. In 2004, the triathlon competition for the Athens Summer Olympics took place in the Vouliagmeni area. The suburb has also attracted famous visitors: in the summer of 1964, Bob Dylan stayed in Vouliagmeni and composed many of the ballads later recorded for the album Another Side of Bob Dylan. The suburb has hosted the annual Bilderberg Group meeting twice, in 1993 and 2009. Tennis player Stefanos Tsitsipas was raised here. The combination of exclusivity and beauty draws people who want to be near Athens without being in it.