Rental car from Athens

Something isn't clear: why would you want to return the car in the Peloponnese if the end of our trip is Hydra?

In what order are you going to Athens, Hydra, and the Peloponnese?

We are taking 3 weeks and prefer of spending a week on Hydra. Just to experience the culture and rest after the car touring and busy Athens. So Hydra is at the end hopefully. The latest Greece guidebook states you can take a ferry from several cities on the Peninsula.

There are only two ports in the Peloponnese from which you can take a ferry to Hydra: Ermioni and Porto Heli.
The ferries departing from these ports go to the port of Piraeus, stopping at the islands in the Saronic Gulf.

Pop's Car is the only car rental company that would allow you to rent a car in Athens and return it in Ermioni or Porto Heli (or vice versa).

Regardless of the order in which you visit the places you mentioned, Hydra cannot be your final stop since you will have to return to Athens to get home.

In my opinion, another option, if I understand correctly what you want to do, would be to rent a car in Athens to travel to the Peloponnese, then return it to Athens (or the port of Piraeus) and from there take a ferry to Hydra the same day. Finally, return to Athens by ferry.

I can’t answer your logistics question but for whatever it’s worth we had a good experience with Athens Car Rental in October. We picked up the car in downtown Athens at our hotel and dropped at the airport two weeks later. Worked seamlessly and received a 2024 car.

Thanks to everyone for the advice . We have found out that Pops rentals can be returned to Ermonias port area.