Porth Diana and Porth Castell are two small sandy coves just a short walk south of Trearddur Bay on Anglesey's Holy Island. Both are backed by a sea wall, and flanked by rocks of mica-schist. Porth Diana (above) is the larger of the two, and much used by the local yacht club for moorings. Porth Castell (below) is just to the south, and is probably a better choice for swimming.
Ravenspoint Road runs behind the beaches and roadside parking is possible further along the lane, but suitable places are readily taken. It's probably best to park as for Trearddur Bay and walk from there.
The photos were taken at mid-tide.