Flooded slate quarry lagoon by the sea.
The Blue Lagoon at Abereiddi is a slate quarry the sea broke into, leaving a deep pool of milky blue-green water ringed by spoil heaps and old workings. It has hosted the Red Bull Cliff Diving World Series three times — in 2012, 2013 and 2016 — off a platform 27 metres up. The cold, deep water suits guided coasteering rather than a casual dip. Porthgain is just along the coast.
