Restored steam locomotives run from Merthyr’s northern outskirts to the foothills of South Wales’ highest summits, a return journey of 9 miles/14km.
Mae’r trenau stêm sydd wedi’u hadfer i’w cyflwr gwreiddiol yn teithio o gyrion gogleddol Merthyr hyd at odre copaon uchaf de Cymru.