There are daily buses from Athens to Ermioni, either direct, via Nafplion or Kranidi. Buses from Athens to Ermioni depart from Kifissos KTEL Bus Station and the trip lasts for 3 hours. To go to Kifissos KTEL Bus Station, passengers have to take Bus 051 from Omonoia or Bus X93 from the airport of Athens.
There are also very frequent bus itineraries from Nafplion to Ermioni. The trip takes about 1 and half hour. These bus itineraries are more frequent in summer.
Travel to Ermioni by car
To go from Athens to Ermioni by car, you follow the National Highway Athens-Corinth and just after the Corinth Canal you follow the signs to Epidaurus-Ermioni-Porto Heli. You pass Epidaurus and Kranidi and then continue to Ermioni. The road trip is about 3 hours. After the Corinth Canal, the road is not a highway but rural and has only one line per direction, so extra attention is needed.