The source of the Nestos River is on Mt Rila in Bulgaria. The river flows down into Greece through the prefectures of Drama, Xanthi and Kavala and in Greece forms a natural border between the regions of Macedonia and Thrace, and flows into the Sea of Thrace, north of the island of Thasos. Of its total length of 234 kilometers, 130 are in Greece. The biotopes along its banks are home to 150 species of fauna. Fifty tributaries flow into the Nestos, the largest of which are the Despatis, the Arkoudorema, Diavolorema and Mousdarema. Its catchment area includes 212 communities, 119 of them in Greece. Its Narrows (Stena) are protected as an aesthetic forest. The «Nestos Delta and Adjoining Lagoons» was declared a protected area in 1974 under the Ramsar treaty, as a wetland of international interest comprising an extensive delta complex, including salt marshes, freshwater lakes, coastal lagoons, dune systems and the largest remaining area of riparian forest (i.e. adjacent to a body of water) in Greece.