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 large flat area behind the beach was the site of a Celtic iron age settlement at around 300BC, now it's a good place to sit and take in the views. Access to the beach is down a steep 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 coast path, by which time the beach will have come into view.