At the airport plan to arrive a minimum of 2 hours before the departure of your flight. If you can arrive before 4:00 it will be even better, especially if you have luggage to check in.
On the left of the checkin desks there is an automatic kiosk where you can print your boarding pass and baggage tag yourself. There is a dedicated baggage conveyor to drop off your luggage.
About the ferries
If you already have your ticket, make sure to be at the boarding pass at least 30 minutes before departure.
Ferries do not wait for late passengers.
For the Cyclades the Blue Star ferries leave from Gates E6 and E7, to the Dodecanese islands it is from Gates E1 E2.
If you take a taxi, inform the driver of your departure gate, he will drop you off right in front of the boarding area.
By metro, leaving the Piraeus metro station you will be right next to Gates E6/E7 for the Cyclades islands (5 minutes walking distance)
For each Gate all departures are displayed on large electronic displays.
Departure time and destinations are also displayed in Greek and English on large electronic displays on the ferry itself
The disembarkation and the embarkation are done as quickly as possible sometimes in an incredible mess of passengers, trucks, cars, which disembark and embark. So be ready to board when the ferry arrives.
If you have luggage, you will have to leave it on shelves located on the cars deck before going up to the passenger decks.