A section of coast at the tip of the Llyn peninsula together with the island of Bardsey and the smaller Gwylan islands. The coastline is rocky with many crags, screes and low cliffs. Maritime heathland dominated by Calluna and Ulex is diversified by flushes and adjoining grassland. A rich fern and bryophyte flora occurs on Bardsey, whilst sea spray and guano influence the Gwylan flora. The site is important for breeding seabirds and other cliff-nesting species.