Porthdinllaen is a tiny fishing hamlet at the end of a sandy spit on the north coast of the Llŷn Peninsula, reached on foot along the beach or across the golf course from Morfa Nefyn. It was once meant to become a major port, and ships were built on the shore in the 1830s and 40s while the Caernarfon slate trade boomed. The Tŷ Coch Inn has served drinks with sand underfoot for almost two centuries; its Edwardian landlady, Mrs Jones, also ran a girls' school and served as harbour master. Sand martins nest in the soft cliffs, grey seals fish off the headland and one of North Wales's largest seagrass meadows lies beneath the sheltered bay. The Porthdinllaen marine trail is a 2.5-mile loop from the Morfa Nefyn car park, with a signed diversion while the path past the lifeboat station is closed. Dogs are welcome, on leads near the inn and on the golf course, with seasonal limits on part of the beach. Reviewers love the swimming and the rock pools at low tide. Tips from visitors: steep steps lead down to the beach, and there are no bins, so take litter home.