Snowdon, Welsh Yr Wyddfa, highest mountain of Wales, 3,560 ft (1,085 m) high, Gwynedd, NW Wales. Its five peaks are separated by passes. There is a rack and pinion railway (opened 1896) from Llanberis to the summit. The Snowdon district, or Snowdonia, is noted for its scenic beauty; most of it is included in Snowdonia National Park (est. 1951). A nuclear power station (500,000-kW capacity; completed 1964) and a hydroelectric power project are in the region.