Salween River much of its length, the Salween's course is nearly parallel to that of the much larger Mekong in the east. Although the commonly accepted name is Salween, the river is known by a handful of other names regionally: "Nu" in China, "Thanlwin" in southern Burma, and "Salawin" on the border of Thailand and Burma. Several major sub-continental drainage basins border on the Salween. The Mekong basin forms nearly the entire eastern boundary of the watershed, while the Irrawaddy River flows southwards on the west side of the basin. The smallest boundary is formed by the Yangtze to the extreme north.
Nestos (river) is , of which 66% in Bulgaria. It forms some gorges in Rila and Pirin. The Mesta's longest tributary is the Dospat (Bulgarian: Доспат; Greek: Δεσπάτης, Despatis). The banks of the river are covered mainly by deciduous trees that extend into halfway between Bulgaria and Greece where it forms the modern boundary of Greek Macedonia and Thrace, as well as the boundary between the Kavala and the Xanthi regional units, having first crossed the Drama regional unit. The river later forms a delta to the north where swamplands, wetlands and a lagoon once existed except in the east. In the