The Cape Foulwind Railway was a branch railway line west of Westport to Cape Foulwind. In 1886 the Westport Harbour Board built the line to their quarry to transport rocks to their breakwaters in the Buller River. In 1888 it was linked to Westport by a road-rail bridge over the Buller River. About 1890 passenger services were started. In 1914 a new section of line including a tunnel was built to a new quarry south of the Cape.
In 1921 the line and the three F class locomotives were transferred to the New Zealand Railways. The branch was one of the branch lines closed by the Railway Commission in 1930, although it had been effectively closed from about 1925. But in 1931 the line reverted to the Marine Department, which ran occasional trains until about 1940.
Originally the site of a Maori village named Omau, Cape Foulwind has a lighthouse, and a large cement works. Built since the line closed, the cement is trucked from the works to a private siding just south of Westport. The name Omau has been reinstated as a proper place name.