If you own or rent a car, you can easily get from Athens to Poros in appoximately 2 hours. Through Attiki Odos, get on the National Road Athens – Corinth and make a left after the canal heading towards Epidauros (Corinth Exit 10 - Epidavros).
Drive for about 30 minutes and you reach the intersection of Epidaurus. Before getting there, you will see signs to Poros or Spetses. At the junction turn right and immediately drive under the bridge and make a left.
Then, follow the new road, making sure you don’t miss the sign to Poros. At this point, slightly turn left for Poros and you will reach Galata in 25 minutes, via the coastal road, from where you can hop on a small ferry to Poros.
The road is an extension of the highway, good enough for the entire journey, with an average speed, it takes about 2 hours to get there.The small ferries from Galata departures run every 30 minutes and the fare is about 4 €, including the driver.
There is a big public parking, which is free, where you can leave your car in case you want to go across Poros by boat in 5 minutes. The fare costs about 1 € per person.