Treginnis walk
This walk takes you over Wales’ oldest rocks - laid down some 600 million years ago during the Pre-Cambrian era. They're volcanic in origin, covered in places by layers of younger, sedimentary Cambrian rocks.
Map
Start:
Porth Clais Harbour, grid ref: SM741242
1
Turn right as you leave the car park, walking up the road past high blackthorn hedges.
2
At the crossroads, turn left (signposted Treginnis). The landscape is dominated by the igneous outcrops of Carn Llidi, Carn Trefeiddan and Pen Beri. As you pass Treginnis Lodge, Skomer Island comes into view to the south across St Bride's Bay.
3
At the sign for Pencnwc Farm, turn right off the road and immediately left, following footpath sign to Porthstinian/St Justinian. Walk through a patch of scrub woodland and past a National Trust sign for Treheinif. After about 55yd (50m), go through a metal gate and follow bridleway signs around the field edge.
4
Continue to follow the footpath out of the far corner of the field, then immediately right through a metal gate. Carn Rhosson (topped by a white pole) and the North Bishop come into view as you walk towards the sea and Ramsey Island. Turn right through a metal gate, along a track and through another metal gate onto the short section of road to St Justinian.
Ramsey Island
Look ahead for the spectacular island of Ramsey, whose twin peaks are the remains of long extinct volcanoes. Ramsey is separated from the mainland by the fierce currents of Ramsey Sound.
5
At St Justinian tour the Royal National Lifeboat Institution (RNLI) station, if open. A new one is being built in the cove immediately south of the old one. St Justinian is the start point for boat trips to Ramsey. Turn left onto the coast path, where you'll be for the rest of the walk.
6
Along the coast path you'll see a small promontory, a coastal Iron Age fort called Castell Heinif, with weathered ramparts just discernible. Continue south through two more kissing gates. After the second, the path bears right past Seal Bay - look out for seal pups in late summer and early autumn.
Wales' oldest rocks
Wales' oldest rocks - of the Pre-Cambrian era - dominate the peninsula. These are volcanic in origin, covered in places by layers of younger, sedimentary Cambrian rocks.
7
A steep descent past a short fenced section of cliff brings you to an open grassy area and the ruins of a 19th-century copper mine. Follow the coast path south and then east. As you bear left you can see Skomer, Midland Isle and the Marloes Peninsula in the distance.
8
Round the corner you walk through some fine coastal heathland and down to the rocky cove of Porthlysgi, an area noted for its shipwrecks. Just east of Porthlysgi, see if you can spot the picrite boulder, a glacial erratic boulder transported here by ice and believed to originate from Scotland. Follow the coast path round to Porth Clais Harbour and back to the car park.
Porth Clais Harbour
Porth Clais is the only harbour between Solva and Porthgain. The cliffs and slabs to the east of the harbour entrance are a popular climbing spot. Don't miss the Kiosk in summer, for ice cream and great homemade cake.
End:
Porth Clais Harbour, grid ref: SM741242
