Murlough National Nature Reserve protects a 6,000-year-old sand dune system on the edge of Dundrum Bay beneath the Mourne Mountains, managed by the National Trust as Ireland's first nature reserve since 1967. Its dune heath is the best and most extensive in Ireland, home to over 720 species of butterflies and moths including the marsh fritillary, and the bay is internationally important for wintering wildfowl and waders. Paths and boardwalks run through dunes, woodland and heath, past grazing cattle and horses, to a four-mile beach, and a natural play area has wooden sculptures and a log sofa. Dogs are welcome on leads, with a seasonal ban on the Blue Flag stretch of beach. Reviewers single out the ten-minute boardwalk walk to the sand, the lifeguards who cover the swimming zone for part of the year, and the cafe. One tip from regular visitors: the pay and display machines are cashless, and members must scan their card and key in their registration to park free. Toilets are not open year round.