From the Athens International Airport you may reach Hydra by: Metro,Bus or taxi to the port of Piraeus and thereon by flying dolphin or catamaran to Hydra.
Metro. The metro leaves from the Athens airport metro station every 30 minutes between 06:30 a.m. and 23:30 p.m. Travelers take one metro from the airport to the Monastiraki station in the centre of Athens (~40 minutes). At Monastiraki, you switch to the Piraeus line (green), which terminates at the Piraeus metro station (~30 minutes). The metro station is located a few blocks from the Hellenic Seaways departure gate. For more information, visit the Athens Airport Metro page.
Bus.Once you exit the arrival gate, the public transport bus from Athens Airport to Piraeus Port can be found between exits 4 & 5.The bus from Athens Airport to Piraeus Port is X 96 and leaves approximately every 15-30 minutes, depending on the time of day (Athens Airport Bus), and run 24/7, including holidays.The ride from Athens Airport to Piraeus Port is approximately 45 km and it takes around 90 min.Tickets must be purchased at the ticket kiosk in the bus departure area (outside the airport). The price is 5€, with a half-price ticket for children/students ages 7-18, and seniors over 65. Children under 6 travel free.
Taxi. The taxi rank is to the left as you exit the arrivals area (between Exits 2 and 3). Taxis are available around the clock. There may be a bit of a queue, but it typically moves quickly. The fare from the airport to Piraeus runs around 50€ during the day (5 a.m. to midnight) and 65€ at night (midnight to 5 a.m.).
Flying Dolphin or Cat. On arrival in Piraeus you will catch a hydrofoil or a catamaran to Hydra. The trip takes about 2 hours. You can either book online or call them Hellenic Sea Ways(+30 210 419 9000). You should allow about two (2) hours between landing in Athens and your boat departure. You can coordinate that by looking at the Dolphins website.
Taxi or car to Metochi or Ermioni (villages on the mainland of the Peloponnese across Hydra).
From Athens International Airport (AIA), the driving distance to Metochi, a village on the Peloponnese across from Hydra, or Ermioni is about 216 km and will typically take just under 3 hours with normal traffic. Taxis are available at the taxi rank outside the arrivals area at the Athens airport. It is also possible to book a taxi through a private service or rent a car.
From Metochi (mainland) you can take the Freedom & Metoxi Express water bus services or hire a private water taxi to Hydra.
From Ermioni (mainland) you can take the flying dolphin or catamaran or again hire a private water taxi to Hydra.
Flying dolphin or catamaran to the port of Piraeus & thereon by metro,bus or taxi to the airport.
Private water taxi to Metochi or Ermioni & thereon by taxi to the airport.