The River Ant is a tributory of the River Bure.
At the beginning of Coot Club, Mrs Barrable and the Ds go by boat from Wroxham to Horning and to the Teasel. The boatman says: A good nursery for sailing is the North River and a footnote explains that This is another name for the River Bure (CC2).
There is a map of the River Bure in Coot Club (CC9). On the map, there is a note by "N.B." saying Navigable waters shaded. Places where people are not allowed to sail are left out of this map.