The first record of Barmouth (or Abermaw) as a small port was in 1565. Subsequently, Barmouth developed as one of the major ship building centres in Wales during the 18th and 19th centuries.
The Barmouth Harbour Trust was founded by Act of Parliament in 1797, `for repairing, deepening and preserving the Harbour' . which was then improved in 1797-1802. The shipping interests of Barmouth appear to have pioneered the extensive London slate trade around 1800. Barmouth continued as a shipbuilding centre until the 1820's, when Porthmadoc, to the north, dominated as a slate port.