Kea, which Greeks usually call Tzia, is the Cycladic island closest to Athens, and this is the crossing that makes it a weekend habit for so many Athenians. Only about 13 nautical miles of water separate Korissia, the island's port, from Lavrio on the south-east tip of Attica, so the whole trip home takes about an hour on the water.
Kea is hilly and quiet, with old footpaths, the hilltop capital Ioulida and a handful of calm bays, and it has kept a Greek rather than an international feel. Most visitors come for a few days of walking, swimming and eating, and many combine it with Kythnos, the next island south.
On the mainland side, Lavrio is a small port town about 60 km from central Athens and around 35 km from Athens International Airport. That makes it closer to the airport than to the city, which is useful if you are flying out, but it also means the journey into central Athens by bus is longer than the ferry itself. Plan the road leg as carefully as the sailing.
The route runs every day, all year, with several departures on most days from early morning until late evening. Even so, the boats back to Lavrio are in heavy demand in high season and at the end of long weekends, when many Athenians head home at once, so book ahead for those dates, and much earlier if you have a car.
