The Panachaicus (Greek Panachaïkos, Voidia in medieval, post-medieval and until the beginning of the 20th century.) is a mountain range that spans about 20 km in length from north and south (Glaukos, to the Psathopyrgos, and 15 to 20 from east to west (east of Patras to west of Selimantika. It is the northernmost mountain range in the Peloponnese. The highest point is 1,928 m, some marked it at 1,924, 1,925, and 1,926 m. The mountain is home to the skiing resort which can be seen from almost all of Patras.

Villages and towns like Ekilistra, sections of Romanos, and parts of Kriatsi is on the mountain range, though not on the mountaintop.

A view of other mountains from the top like Oites, Erymanthos, Chelmos/Aroania, and southwestern Central Greece mountains can also be seen from the top.

See also List of mountains in Greece, List of mountains.