Three dredged channels some 185m long and 18m wide provides access to a large quarry with interconnecting galleries/floors. The easternmost channel former;y branched into two well-defined docks at SN02740611 and SN02760608. The central channel formerly had a dock at SN02680601 and a secondary channels running parallel to it on its eastern side for part of its extent, possibly as a way of regulating vessels in and out. The westernmost channel formely had a dock at SN02660601 and waiting docks half way along its length at SN02630615 and SN02650610. Close to the main entance, this main channel branches to the west to serve another large gallery/floor with a dock at SN02590608. As the quarry expanded westward, another dock appears to have been provided at SN02530607. Modern aerial photography still shows the cut channels very clearly.

Williamston Park Quarry was a source of limestone from around the late C18th and activity continued until the early C20th. The result of this industry is a peninsula deeply cut by channels created to allow boats to enter and load up with stone. These cuttings now survive as tidal creeks some still opening out onto old quarry workings which have become salt marsh. Some of the cuttings have silted up or dried out and been invaded by scrub. A small area of channels at the south have been reclaimed and turned into pasture. Between most of the channels are none too obvious former spoil tips, very overgrown, but there are one or two surviving quarried rock faces as well as natural limestone outcrops.
According to Moore Colyer the stone from this quarry was in great demand for agricultural use (lime burning) as well as furnishing building stone for Milford docks and military works on Milford Haven. Accessibility of the raw material was a major factor in its exploitationin this particular area.

Sources include:
NAW aerial photography 2006-9
OS 1st edition 25in mapping
J Latham, Williamston Park, Report for the NT, 1987.

Maritime Officer, RCAHMW, May 2012.