Mynydd Blaengwynfi

About Mynydd Blaengwynfi

Mynydd Blaengwynfi is a South Wales workhorse overlooking the Afan Valley. It lacks the jagged drama of its northern cousins, but it makes up for it by hiding a massive, decaying Victorian railway tunnel beneath its skirts. It's the ideal spot for hikers who enjoy industrial heritage and a bit of mist.

Key Statistics

Find It

Did You Know?

• •The Rhondda Tunnel sits nearly 1,000 feet directly below the surface of this fell. It was once the third-longest railway tunnel in Wales, stretching over 3,400 yards through the dark rock.
• •Construction started in 1885 but was nearly derailed by constant water seepage and a lack of willing workers. The project was only saved when the original contractor was replaced by the more aggressive Lucas and Aird firm.
• •Local mining activity was so intense that the mountain literally squeezed the tunnel, distorting its lining over time. Between 1938 and 1953, engineers had to install 500 steel ribs just to stop the tunnel from collapsing entirely.
• •After being sealed with rubble in 1980, the tunnel has become a legendary 'lost' site for historians. Current plans hope to excavate the portals and transform the dark depths into a spectacular underground cycleway.
• •Hiking here involves a constant game of 'guess where the ventilation shaft is' before you accidentally descend 60 feet into history. The local sheep appear to be the only ones who know the reopening date, though they remain tight-lipped.