The Rhondda Tunnel Society volunteers taking part in their monthly inspection of the disused tunnel which links Blaencwm in the Rhondda Valley and Blaengwynfi in the Afan Valley.
Completed in July 1890, the 3,443 yard tunnel was used to transport coal from the Rhondda to Swansea docks, now the society want it to re-open as a walking and cycle route.
Ben Salter who returned to the tunnel to find graffiti he had written on the tunnel wall in 1973
Picture by Richard Williams