There are many scheduled itineraries to and from the Port of Piraeus every 20
You can take the: Ε96-PEIRAIAS/AEROL. ATHINON (EXPRESS LINE).
The ticket cost is about 2,90€ per person.
You can buy it from the bus kiosk near the bus stop and stamp it in the bus.
The bus-trip to Piraeus it will take (depending on the traffic situation) about 60 min.
The buses to Piraeus and Athens run 24 hours a day.
The Port of Piraeus is the last stop: "Piraeus - Platia Karaiskaki".
From there you have to walk 5 minutes to the part of the Portwhere the ships for Hydra leaves from.
(In the point called: "Agios Spyridon").
From "Eleytherios Benizelos" you can reach the port of Piraeus with
taxi, in only half an hour.
The price is aproximately 30€ to 35€.
With the same means of transportation, you can go from the main port of Riraeus
to the National airport "Eleytherios Benizelos".