Treginnis walk

Walking trail

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.

Treginnis Peninsula and Ramsay Island


Map route for Treginnis walk


Porth Clais Harbour, grid ref: SM741242


Turn right as you leave the car park, walking up the road past high blackthorn hedges.


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.


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.


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.

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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.


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.

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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.


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.

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Porth Clais Harbour, grid ref: SM741242

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Treginnis walk


Moderate to rugged paths with some rocky sections.

Dogs must be on leads, sheep are often on the coast path.

Treginnis walk

Contact us

Treginnis walk

How to get here

Porth Clais Harbour, Pembrokeshire, SA62 6RR
By train

Haverfordwest, 20 miles (32km); Fishguard, 19 miles (30km).

By road

1.5 miles (2.4km) south-west from St David’s, follow signs for Porth Clais. Post code SA62 6RR.

By bus

Routes 342 and 411, Haverfordwest to St David’s; Puffin Shuttle 400, Solva, Marloes and Milford Haven to St David’s; Strumbe Shuttle 404, Fishguard and Newport to St David’s. Then catch Celtic Coaster shuttle bus from St David’s to Porth Clais.

Treginnis walk

Facilities and access

  • Dogs welcome, but please keep them on leads as livestock are grazing