The river begins in the Tymfristos mountains on the border with Evrytania and flows to the east through the village Agios Georgios Tymfristou, entering a wide plain. It flows along the towns Makrakomi and Leianokladi, and south of the Phthiotidan capital Lamia. The river flows through an area of former wetlands, that have been reclaimed for agriculture. It empties into the Malian Gulf of the Aegean Sea 13 kilometers (8 mi) southeast of Lamia. In antiquity, the mouth of the river was the site of Antikyra, which was famed for its black and white hellebore.
Several studies have been conducted regarding the river's hydrological regime.[4] Its silt has slowly filled the Malian Gulf, turning Thermopylae from a narrow pass into a wide plain.