The River Cam is the main river flowing through Cambridge in eastern England. After leaving Cambridge, it flows north and east into the Great Ouse to the south of Ely at Pope's Corner. The Great Ouse connects the Cam to the North Sea at King's Lynn: The total distance from Cambridge to the sea is about 40 mi (64 km) and is navigable for punts, small boats, and rowing craft. The Great Ouse also connects to England's canal system via the Middle Level Navigations and the River Nene. In total, the Cam runs for around 69 kilometres (43 mi) from its furthest source (near Debden in Essex) to its confluence with the Great Ouse.
The original name of the river was the Granta and (unusually) its present name derives from the city of Cambridge (Old English: Grantebrycge) rather than the other way around: After the city's present name developed in Middle English, the river's name was backformed to match. This was not universally applied, however, and the upper stretch of the river continues to be informally known as the Granta. It has been said that the river is the "Granta" above the Silver Street Bridgemap 11 (in Cambridge) and the "Cam" below it. The Rhee tributary is also formally known as the Cam,[dubious ] and the Granta has a tributary on its upper stretch also known as the Granta.
An organisation called the Conservators of the River Cam was formed in 1702, charged with keeping the river navigable. The Conservators are responsible for the two locks in and north east of Cambridge: Jesus Lockmap 7 and Baits Bite Lock.map 3 The stretch north (downstream) of Jesus Lock is sometimes called the lower river.
The stretch between Jesus Lock and Baits Bite Lock is much used for rowing. There are also many residential boats on this stretch, their occupants forming a community who call themselves the Camboaters.
The stretch above Jesus Lock is sometimes known as the middle river (with the section above the Mill Pond being referred to as the upper river). Between Jesus Lock and the Mill Pond,map 12 it passes through the Backsmap 10 below the walls of many of the colleges. This is the section of river most popular with tourists, with its picture-postcard views of elegant bridges, green lawns and graceful willows. This stretch also has the unusual feature of the remains of a submerged towpath: the riverside colleges did not permit barge horses on the Backs, so the beasts waded up the Cam to the mill pulling their loads behind them.