Having Ermioni as your base, you can organize excursions to Ydra (20 minutes by boat), Spetses (15 km To Kostas and then 10 minutes by boat), Poros (40 km or 1 hour by boat), Porto Heli (15 km), Porto Ydra by canals (12 km), the ancient theatre of Epidaurus (50 km) or even Nafplio (80 km).