This is a selected list of the oldest rivers on Earth for which there is knowledge about their existence in past times.
Generally, the estimate of the age of a river is based primarily upon the age of any mountains that it dissects. The age of the sea or ocean to which it eventually outflows can be irrelevant; for example, several rivers of the east side of the Appalachian Mountains are thought to be older than the Atlantic Ocean into which they flow. If a river fully dissects a mountain range, then this generally indicates that the river existed at least at the time that the mountain range rose.