The Dwyryd River Navigation (NPRN 91424) consists of some seven kilometres of navigable river and includes the Cemlyn Canal (NPRN 91427) and various riverside wharves or quays between Maentwrog Bridge (NPRN 24191) downstream to Pont Briwet (NPRN 404539). It was last used commercially in about 1873; the principal traffic was slate, but timber, limestone and coal were also carried.
Cei Tyddyn Isaf is situated on the north side of the river; the quay is some 206m long and there are two magazine buildings, one at the southern end and one towards the northern end.
B.A.Malaws, RCAHMW, 18 August 2009.

Statement of Significance:

A network of roads, in use, and relict quays on the Dwyryd river were the means by which slate from the Ffestiniog quarries was transported to Porthmadog harbour for onward transhipment (NPRN 306317) before the building of the Festiniog Railway (NPRN 34660).   

The cart roads and slate quays on the Dwyryd river are part of the Slate Landscape of Northwest Wales World Heritage Site, Component Part 5: Ffestiniog: its slate mines and quarries, slate town and railway to Porthmadog. Inscribed July 2020.  

Sources:  

• Louise Barker & Dr David Gwyn, March 2018. Slate Landscapes of North-West Wales World Heritage Bid Statements of Significance. (Unpublished Report: Project 401b for Gwynedd Archaeological Trust) 
• Tirwedd Llechi Gogledd Orllewin Cymru / The Slate Landscape of Northwest Wales. Nomination as a World heritage Site (Nomination Document, January 2020) 
• Wales Slate World Heritage Site https://www.llechi.cymru/

Hannah Genders Boyd, RCAHMW, February 2022