Blue Lagoon

The ruins of Abereiddy slate quarry sit on the northern edge of Pembrokeshire in South Wales. One of more than a hundred quarries in the county that operated in the late 18th century, slate that was extracted from Abereiddy was transported by tramway to the neighbouring Porthgain Habour and shipped out to sea. The quarry itself was active until the early 20th century and later abandoned and deliberately flooded when the channel connecting the quarry to the sea was blasted using explosives, allowing the sea to flood in. Ruined quarry buildings still sit on the clifftop, including Abereiddy tower which is one of the oldest structures believed to be late 17th century and is thought to have been built as a lookout beacon for ships using St George's channel.