Briton Ferry Dock was constructed to designs by Brunel and opened in 1861. It comprises an inner floating dock, with an area of some 13.2 acres (5.4 hectares) and an outer tidal basin with an area of about 10.5 acres (4.25ha). Entry to the dock was through a single buoyant lock gate (nprn 34238). It closed in 1959 and in 1989 was noted as largely silted up although the walls were intact. Still to be seen are the partially dismantled lock gate and, on the eastern side of the dock, the square tower of the engine house which generated hydraulic power for its operation.
(Sources include: "A Guide to the Industrial Archaeology of the Swansea Region", Association for Industrial Archaeology, 2nd Edition, 1989)
The inner basin, now largely filled in, was crossed at its northern end by the Neath by-pass bridge (nprn 91604) in 1955 and in 1993 by the M4 motorway viaduct further south.
B.A.Malaws, RCAHMW, 17 March 2014.