Sychryd or Afon Sychryd Starts just below Graig y Llyn and is know localy as the Nant Gwrangon it flows past the village of Rhigos and through Cwm Wyrfa on the edge of the Brecon Beacons National Park and Fforest Fawr Geopark in the county borough of Rhondda Cynon Taf in south Wales. under the A465 Heads of the Valleys Road and turns northwest to join the Afon Mellte at Pontneddfechan. [1]
Its lower section is cut into a spectacular gorge beneath Craig-y-Ddinas or Dinas Rock, site of an Iron Age hillfort and of the once-famous Dinas Silica Mine. The gorge is well used by gorge-scramblers though there has been concern that their activities can cause damage to the rare bryophytes and mosses that colonise the rocks in this shaded valley and for which it has been designated as a special area of conservation.
There are several waterfalls of note on the river including those at Pwll y Crochan near the A645 and Sgydau Sychryd beneath Craig-y-Ddinas. The former is hardly accessible to the public but the latter is easily seen from the Sychryd All-ability Trail which follows a former tramroad up the river from the car park at Craig-y-Ddinas. It is falls such as these that have resulted in the wider area becoming known as Waterfall/s Country.