The Blyth Navigation was a canal in Suffolk, England, running seven miles from Halesworth to the North Sea.
Following an Act of Parliament, which was passed on 1 April 1757,its construction was completed in 1761 at a cost of £3,000. It initially had four locks; a fifth was added later. From the sea, the Navigation follows the River Blyth until it reaches the Town River, which it follows to Halesworth Lock. From here, the New Cut took the canal to a wharf at Halesworth, which formed the terminus of the canal. The New Cut joined back up with the Town River a little further to the west, in order to provide the water supply for the locks.
In order to allow wherries to reach his maltings, a local maltster named Patrick Stead increased the water levels above the point where the New Cut and the Town River joined, by building an additional lock near the junction.
The locks were constructed to allow wherries to use the navigation, and so were 50 ft long and 14 ft wide (15.2 x 4.3m). However, they were unusual, in that the side walls curved outwards in the centre, to provide an extra 1.5 ft (0.45m) of width.
Navigation ceased in 1934. Some efforts have been made since to restore it, but the resultant flooding of bordering land has made this unpopular.
