There’s a great legend explaining the existence of the chapel, and more interesting, the unusual markings in the cliff face. The information board at the car park above the chapel only tells part of the story:
Tradition says [St Govan] was pursued by pirates [or Vikings] to the cliff edge where the chapel now stands. Miraculously, a cleft in the rock opened for the Govan[sic] to hide in, closing again until the marauders had left.
The place where St Govan hid is now the anteroom at the back of the chapel, and the strange markings in the cliff show where his ribs were pressed against the rock when God hid him.