Wharves for the shipping of slate from the Dinorwic slate quarries were established along the narrow estuary of the Afon Heilyn from the late 18th century. The dock was constructed between 1897-1900, designed and overseen by civil engineer Frank Oswell. The 350 metre-long dock was crossed by a single-leaf bascule bridge, at the site where there had been a swing bridge across the estuary. At the end of the dock were ship-repair facilities with a graving-dock, with stepped sides and a polygonal inner end and formerly closed by an iron caisson. Some of the quayside bollards and lock sluice operating gear are marked 'Cleghorn & Wilkinson, Engineers, Northwich'. The dock is now a marina, with new housing on the south side of the upper basin.
W J Crompton, RCAHMW, 28 October 2009.

Port Dinorwic Docks, Proceedings of the Institution of Civil Engineers, Vol. 147, 1902.

Term Engineering Studio, Proposed Renovation and Repair Works - Port Dinorwic Bascule Bridge, 2024