The Mournes are visited by many tourists, hillwalkers, cyclists and rock climbers. Following a fundraising drive in 1993, the National Trust purchased nearly 5.3 km2 (1,300 acres) of land in the Mournes. This included a part of Slieve Donard and nearby Slieve Commedagh, at 767 m (2,516 ft) the second-highest mountain in the area.
The Mourne Wall is among the more famous features in the Mournes. It is a 35 km (22-mile) dry-stone wall that crosses fifteen summits, constructed to define the boundaries of the 36 km2 (8,900-acre) area of land purchased by the Belfast Water Commissioners in the late nineteenth century. This followed a number of Acts of Parliament allowing the sale, and the establishment of a water supply from the Mournes to the growing industrial city of Belfast. Construction of the Mourne Wall was started in 1904 and was completed in 1922.
Some of the mountains have names beginning "Slieve", from the Irish word sliabh, meaning "mountain". Examples are Slieve Donard, Slieve Lamagan and Slieve Muck. There are also a number of curious names: Pigeon Rock; Buzzard's Roost; Brandy Pad; the Cock and Hen; Percy Bysshe; the Devil's Coach Road; and Pollaphuca, which means "hole of the fairies or sprites".
The Mournes are very popular as a destination for many Duke of Edinburgh's Award expeditions and those taking part in the Mourne Mountain Challenge.
The Isle of Man, the mountains of the Lake District, and Snowdonia in Wales can sometimes be seen across the Irish Sea from some parts of the Mournes on clear days. The mountains are also visible from parts of Dublin and Galloway on clear days.