Mirtia, Greece offers 1 beach perfect for sunbathing, surfing, swimming, and more. Mirtia, Peloponnese, Greece, is known for its proximity to the ancient site of Mycenae. The best time to travel to Mirtia, Greece, is from May to September, with average air temperatures ranging from 75°F to 85°F and water temperatures from 72°F to 79°F. Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!