Porth Trwyn is a small beach on Anglesey's western shore, consisting of low-tide sand and rocks and shingle at the top of the beach. There is usually a line of rotting seaweed which can be somewhat malodorous as well as concealing rock-pools when stepped on. It is situated about 1¼ miles west of Llanfaethlu on the A5025. A small (free) car parking area on stony ground is located between the road and the beach. Access to the shore is along a short track. The coast on either side is indented by numerous small coves.