The Norfolk Broads are a network of over 120 miles of navigable rivers and lakes in Norfolk and Suffolk. There are seven rivers and 63 broads, generally less than 13 feet deep. Thirteen broads are open to navigation and a further three have navigable channels. The Broads largely follows the line of the rivers and natural navigations of the area. The seven navigable rivers are the River Yare and its tributaries, the Rivers Bure, Thurne, Ant, Waveney, Chet and Wensum. There are no operational locks on any of the rivers except for Mutford Lock in Oulton Broad which links to the saltwater Lake Lothing in Lowestoft, Suffolk. All the waterways are subject to tidal influence which decreases with distance from the sea. Highly tidal areas such as Breydon water contrasts with barely-tidal reaches such as the River Ant upstream of Barton Broad. The broads themselves range in size from small pools to the large expanses of Hickling Broad, Barton Broad and Breydon Water. Besides the natural watercourses of the rivers, there is one more recent navigation canal, the lock-free Haddiscoe Cut which connects the Rivers Yare and Waveney allowing boats to by-pass Breydon Water.