Known locally as Sandy Beach, Porth Tywyn Mawr is a sandy bay 800 yards wide, near the village of Llanfwrog. It is backed by dunes with the Penrhyn Bay camping site occupying the southern headland, and the rocky islet of Craig Dafydd in the centre of the bay. Watersports are popular here particularly jet-skiing, windsurfing, canoeing, sailing and surfing. Some roadside parking is available at the end of the lane from Llanfwrog at Grid Ref : SH289850. At the bottom of this lane is the coastal path, and a short track onto the shore. The caravan park has a small shop which is open to the public and sells ice-creams, newspapers, groceries etc. Dogs are allowed at all times. Signs warn of unexpectedly large waves generated by ferry movements at Holyhead.