Mynydd Mawr is prominently positioned on the North-western edge of the Llŷn Peninsula delivering exceptional views of the surrounding area, particularly of Bardsey Island.
From Mynydd Mawr to Pen Y Cil the coastal and near-coastal habitats are subject to a strong maritime influence. Salt-laden wind can cause severe salt-burn to the grassland, leading to ‘wave-formed’ heathland. Along the shoreline, vigorous wave action has a marked effect on the rocks and the surviving plants and animals.
The cliffs and western coastal heath encompass plant communities that enthuse special interest, including Bell Heather and Western Gorse. Between and within the heathland blocks, maritime grassland communities and localised flushes on boulder-clay slopes provide contrasting flora and intensified biodiversity. Rare and uncommon plants include Spotted Rock Rose and Prostrate Broom (found as an isolated outlier to the north). Golden Samphire, Lanceolate Spleenwort and a highly localised sub-species of Sea Lavender also occur on the cliffs. Notably, two rare heathland lichens have been recorded in the area.
Among the various birds observed, Chough is of particular interest. Sea caves provide nest sites; the cliffs provide roosting sites while grazed rough grassland and heathland offer feeding areas. Cliff-nesting sea birds are also supported including species of gull, Guillemot, Razorbill, Fulmar and Peregrine. Bottlenose Dolphins are regularly seen (best in summer), along with more occasional sightings of Risso’s Dolphin and Harbour Porpoise.
The rocky shore offers an interesting insight into the rich marine biology of the area, including bedrock cliffs that reveal awesome wave-exposed rock habitat and its associated marine communities located between Bardsey Island and the Great Orme. Community zonation typical of this habitat occurs along roughly 8km of the coast.
A road to the summit, owned by the National Trust, was built during the Second World War to provide access to the heights, where men were posted to give early warning to Liverpool of Luftwaffe air raids. The former Coastguard lookout point, staffed for almost 80 years before becoming redundant in 1990, provides views over Bardsey Sound to the island. The hut contains an exhibition to the natural history of the area, and a mural created by local children.
There is parking at Mynydd Mawr but it is limited.