panorama of the danube waters in belgrade, serbia, with a blue sky. reka dunav, or danube river, is a major river of europe and a

danube river serbia waterway navigation southeastern europe international blue transport central european capitals black sea delta union scenery natural border water traffic commercial route tent network rhine corridor dunav reka renak panorama landscape inland waterways serbian nature aquatic ecosystem freshwater resource hydroelectric power ecological shipping tourism biodiversity basin fluvial environmental confluence cultural significance historical trade transeuropean riverbank riverine