Start National Park Visitor Centre GR977 262
Turn L out of car park and then R at JN. At next JN turn L. SO for over just 1km and trun R onto grassy BW. SO for 0.75km and turn 90 degrees L onto grassy lane. SO down lane which becomes rougher and steeper. Turn L at bottom and follow lane for over 1km and just before main road turn R up BW. SO uphill for 1.5km and out into open hill area. Follow BW to L along top of hill, bearing R and down to Dan y Cefn Farm.
Onto metalled road and turn L and SO for nearly 2km into Defynnog.
At main road turn R then at next main road turn L. SO and over bridge. At end of houses turn L. Follow minor road, which becomes track for over 2km to metalled road. Turn L then R then fork R and SO for 2km. Just before Heol Senni turn L. After 1 km turn R at crossroads. Follow road then stone track to JN. Turn sharp L and SO for 2.5km out onto metalled road. SO for 1km to main road. Go straight across and onto track. SO for 1.75km on track and back to Centre.