Geropotamos, the sacred river of the Minoans as its name imposes (ieros potamos means sacred river), gathers the water of Mesara Plain, being the river with the largest drainage basin in Crete. The main river and its tributaries cross the regions of the ancient cities of Phaestus and Gortyn. The main river essentially starts a little west of Asimi, while the most important tributaries are Stalianos starting from Megali Vrisi, Litheos River which passes through ancient Gortyn and Koutsoulidis which originates from the valley of Rouvas and feeds the dam of Faneromeni.
River Geropotamos exits at the area of the military airport of Tymbaki, to the south of Kokkinos Pirgos. Apart from the main mouth of the river, the wider area of its estuary creates a series of fragmented wetlands of unique beauty and ecological value, which used to be a single whole. The most beautiful of them is located right behind the big beach of Pachia Ammos near Kalamaki. It is an extensive system of ponds and seasonal swamps hosting aquatic plants, impressive reedbeds and a large number of birds. The area of the wetland is separated by a series of dirt roads that are ideal for hiking and bird watching, while the serene beach of Pachia Ammos is wonderful for swimming. Also equally important is the small lake Katalyki that is formed on the borders of Kokkinos Pirgos and the airport.
As Cristoforo Buondelmonti refers in the description of the island of Crete (1415), when he embarked near the exit of the river, he saw the ruins of a small town, which today is not distinct. He may meant the remnants of Kommos to the south.