Castell Bach is a small L-shaped beach, just north of Cwmtydu. It is made up of coarse sand and shingle flanked by cliffs of mudstone with two small islets. A plateau behind the beach was the site of a Celtic Iron Age settlement, now it's a good place to sit and take in the views. Access to the beach is down a steep salebrous path at the north west corner.
Parking is available at Cwmtydu, or slightly nearer roadside parking can be found on the road to St Tysilio's Church at Grid Ref : SN363573. From here, continue on foot to the end of the lane taking the footpath on the left. This leads through a short field to a track. Turn right here, then left at the fork. Continue into the field ahead, looking for a kissing gate on the right. This then leads down to the coastal path, by which time the beach will have come into view.