Porth Clais Harbour sits at the mouth of the River Alun on the south-western tip of the St Davids Peninsula in Pembrokeshire.

The narrow inlet was carved by glacial meltwater around 7,000 years ago and has served as a working port since at least 1385, when it first appears in records relating to building works at St Davids Cathedral.

Goods including limestone, grain, and timber were once landed here, and pilgrims would come ashore to walk to the cathedral shrine. Disused lime kilns remain as evidence of that industrial past.

Today the harbour is a popular access point for kayakers, small boat owners, and walkers joining the Pembrokeshire Coast Path, which runs along both sides of the inlet. At low tide a shingle and sand beach is revealed behind the breakwater.

The site is managed in part by the National Trust, which has cared for the harbour and surrounding land since 1940.