North Pembrokeshire Coast

Abereiddi and the Blue Lagoon

Flooded slate quarry with startlingly blue water, cut through to the sea, and a coast path north to the abandoned quarry village at Porthgain.

Distance: 3.7 mi / 6 km
Time: 2 hr 10
Ascent: 200 m
Difficulty: Moderate
Shape: There and back

Where it is

The circle shows the general area, not the exact start. Use the directions link below to get to the car park itself. Contours and paths shown are OpenTopoMap, drawn from OpenStreetMap data.

The route

From Abereiddi, look into the lagoon then follow the coast path north-east to Porthgain, back down the outward line. Cliff walking with steady ups and downs.

Worth knowing

The lagoon is a deep flooded quarry, popular with coasteering groups. Cold and deep; not a casual swim.
Porthgain at the far end has a good pub and the ruins of the brick and stone works on the harbour.
The black beach at Abereiddi has fossil graptolites in the slate.

What you’ll see

The blue lagoon, quarry ruins, the harbour at Porthgain and its stone hoppers.

Background

Slate was quarried at Abereiddi until 1904, when the sea was let into the workings. Porthgain shipped crushed stone until 1931.