The Wales Coast Path and Lôn Las Cymru (National Cycle Network Route 8) cross the Mawddach estuary on this long timber viaduct, commonly known as Barmouth Bridge. There are fine views of Snowdonia from the path.
The structure was completed in 1867 to enable the Cambrian Railways to convey people and goods along the coast between Pwllheli and Machynlleth. Passenger trains continue to operate on the single-track line, cutting out a long detour by alternative road transport.
In December 1892, part of the bridge caught fire. Newspapers reported that a lad called Owens, who saw the fire when crossing the bridge, ran to the tollgate to raise the alarm. The fire was extinguished, averting “what would have been a serious calamity”, and the youngster was recommended to the Cambrian Railways Board for a reward.
The viaduct is almost 900 metres in length. It consists of 113 wooden spans and four metal spans at the Barmouth end. The metal section, originally of iron, was opened whenever a ship needed to pass. Steel spans were installed here in 1899.
The structure was closed to trains from 1980 to 1986 for repairs. A species of marine worm had bored holes in many of the piles, which are now protected by concrete and glass fibre.
In January 2013 Network Rail, which now owns the viaduct, announced a £5.5m refurbishment programme for the structure, including replacing the four metal spans at a cost of c.£3m.
South of the viaduct is Morfa Mawddach station, where trains to Dolgellau, Llangollen and Ruabon diverged from the Cambrian Coast railway until 1965. The old rail route now forms part of the Mawddach Trail between Barmouth and Dolgellau, as well as part of NCN Route 8.