It starts between the southwestern area of the mountainy place called Rila and of the northwestern Rhodope Mountains in Bulgaria. Then it goes trhough the Pirin mountains and it gets a lot of water from other smaller rivers. It crosses the valley of Nevrokopi and continuous between Orvilos and Rhodope entering Greece through Drama Prefecture. After that it goes to Xanthi Prefecture and cosses a narow and long valley. Eventually at the end, it goes through Xanthi and Chrysoupoli and it drains in the Aegean Sea making a big delta.
It is a natural border between Macedonia and Thrace. It is an important river for the people there because there is a valley so they can water their crops or drink water, take a bath, do watersports etc. Greece and Bulgaria have been arguing for many years about Nestos. After a signed agreement in 1995 the copyrights of Bulgaria are 71% and Greece's 29%. 
- Usefulness and problems of Nestos in Greek