The Blyth Navigation was a canal in Suffolk, England, running 7 miles (11 km) from Halesworth to the North Sea at Southwold. It opened in 1761, and was insolvent by 1884. Its demise was accelerated by an attempt to reclaim saltings at Blythburgh, which resulted in the estuary silting up. It was used sporadically until 1911, and was not formally abandoned until 1934.