Kompsatos is a river flowing in Thrace. It originates from the Rhodope Mountains and the area of ​​Echinos. After following a course of  68 kilometers between steep and inaccessible slopes, it ends in the plain of Xanthi and finally flows into the northern part of Lake Vistonida. According to some scholars, Kompsatos has been identified with the river Kossinitis, which is mentioned in literary works of antiquity. According to mythology, Diomedes' horses turned wild after drinking water from this river.

Kompsatos is an important habitat with a rich fauna of about 130 species of birds, some of which are threatened with extinction.

Between the villages of Iasmos and Polyanthos, the visitor arrives at the stone bridge over Kompsatos, known as Polyanthos bridge, an Ottoman arched bridge that dates back to the 15th century.