The Padarn Railway was a narrow-gauge railway in North Wales, built to the unusual gauge of 4 ft. It carried slate seven miles (11 km) from Dinorwic Quarry to Port Dinorwic. The line opened on 3 March 1843, replacing the Dinorwic Railway. It initially used horses, but was converted to steam haulage on 23 November 1848. The railway was formally titled the Dinorwic Quarries Railway or Dinorwic Quarry Railway, but informally "Padarn Railway" was widely used.