The craggy coastline which runs from the Borthwen beach at Rhoscolyn to Trearddur Bay gives one of the best sea kayaking trips on Anglesey. The cliffs here are not as big as those found at South and North Stack, nonetheless there are plenty of interesting features, including caves and sea arches. Along the coast line there are also numerous islets and islands which provide good sport. There is a beacon on the offshore group of islands beyond the mouth of Borthwen; in the right conditions you can land here too.
Farther round, past the three islands of Mean y sais, Maen-y-fran and Maen yr Esgyll is Rhoscolyn Head. The cliffs here are the most impressive on the whole trip. Make sure you check out the large sea cave just before the headland. This is quite a popular climbing area so you may see climbers scaling the rocks here or in the adjacent Porth Gwalch.
North of Porth Saint are the much photographed White and Black Arches, while further north there are yet more interesting features, such as Porth-y-Cromlech and Porth-y-Garan.
The trip can done in either direction, depending on the time of slack water. The tidal races can be quite strong so careful planning is needed, especially on a spring tide.
There is a small car park at the Borthwen beach, although the approach road is quite narrow and tends to become congested on busy weekends. At Trearddur Bay there is also a car park adjacent to the beach.