The River Ant is a tributary river of the River Bure in the county of Norfolk, England. It is 27 kilometres (17 mi) long (of which 8.75 miles are now navigable), and has an overall drop of 27 metres from source to mouth. It is said that the Ant was formerly known as the River Smale and that this is the origin of the name of the village of Smallburgh. The Ant Broads & Marshes NNR is a national nature reserve.