The harbour at Aberystwyth is the outlet of the united rivers of the Rheidol and Ystwyth. The silt/sandbar at the entrance has impacted on the port's prosperity in times past - for example, in 1561 Aberystwyth was described as `a barred haven of no value?. However, by the eighteenth century, it had a fleet of some sixty small sloops and smacks, with the local fisherman pursuing herring, cod, whiting, pollack and ray during the summer and autumn, and coastal trading during the rest of the year. Trade at Aberystwyth harbour increased so much that in 1763 the Customs House was moved to Aberystwyth from Aberdyfi, and Aberystwyth subsequently became a port of registry. In 1780, an Act of Parliament was passed to further the harbour's development.
In 1836, measures were taken to remove the bar and improve the harbour, so that Aberystwyth could become the homeport for much larger vessels, such as schooners, brigs and barques. Aberystwyth was exporting materials such as lead, zinc ore and tanning bark, and importing coal, limestone, slates, flagstones, timber and household goods. By the 1840s, trading ships were even taking passengers to North America returning with cargoes such as timber.
Aberystwyth also supported a small shipbuilding industry - rope and sail-makers as well as the timber yards and a large saw mill. The total number of ships built at Aberystwyth has been reported as 242. These were primarily the work of three generations of the Evans family; Faulk Evans, his son, John and his grandson, John Faulk Evans.
Admiralty Sailing Directions dating to 1870 noted that Aberystwyth was the homeport for 359 vessels with a tonnage of 39,235 tons. The number of shipping movements in and out of the port in 1868 were 400. It describes the entrance to the harbour as 'defended south-westerly by a pier 260 yards long, extending in a north-northwest direction. The harbour ought not to be attempted by strangers, except in extremity, for the channel in is narrow and turns sharply, and freshes at times materially increase the difficulty of entering? pilots boats crew and warps are constantly ready at tide times'.
The importance of Aberystwyth harbour diminished with the introduction of the railways in the 1860s. The railway provided an alternative route for imports and exports and, as a result, sea trade decreased rapidly. Also, Aberystwyth harbour had insufficient deep water to cater for steam or motor cargo vessels of ever increasing size.
Throughout much of the twentieth century, Aberystwyth harbour has been home to a small fleet of lobster fishing vessels. With the development of the marina in 1990s, the harbour now shelters an increasing number of leisure craft.

Sources include:
Aberystwyth Borough Records, Minutes Books of the Harbours Trustees, F1C, National Library of Wales
Admiralty, 1870, Sailing Directions for the West Coast of England from Milford Haven to the Mull of Galloway including the Isle of Man, pg39-40
Association for Industrial Archaeology, 1984, A Guide to the Industrial Archaeology of Mid-Wales
Jenkins, J Geraint, 1991, The Inshore Fishermen of Wales
Jenkins, J Geraint, 2006, Welsh Ships and Sailing men, pg229-235
Smylie, M, 2005, Working the Welsh Coast
Troughton, W, 2906, Ceredigion Shipwrecks

Maritime Officer, RCAHMW, August 2014.