Tritaia is a former municipality in Achaea, West Greece, Greece. Since the 2011 local government reform it is part of the municipality Erymanthos, of which it is a municipal unit. Population 5,462 (2001). The seat of the municipality was in Stavrodromi. Tritaia was named after the ancient Achaean city Triteia, which was located near the present village Agia Marina. Tritaia is situated in mountainous southern Achaea, on the border with Elis. It nearly surrounds the municipal unit Kalentzi. Mount Erymanthos is located in the eastern part of Tritaia. The Greek National Road 33 (Patras - Tripoli) runs through Tritaia.