Overview
Knockmore (Irish: An Cnoc Mór, “the great hill”) is the highest point on Clare Island – 462 m of it – and also, by the reckoning that lists such things, only the 572nd-highest mountain in Ireland. That undersells it. Because it rises straight out of the Atlantic off the County Mayo coast, it stands a full 462 m clear of everything around it (a “Marilyn”, in hill-bagging terms), and the broad, peat-dotted summit gives you the whole sweep of Clew Bay, its scatter of drowned drumlins, the Mayo mountains across the water and open ocean to the west. It’s a hill walk, not a climb – no technical ground, just a steady pull uphill.
Getting there
Clare Island sits off the Mayo coast, reached by passenger ferry from Roonagh Pier, out west of Westport. It’s a short crossing, but return sailings are limited and fixed by the timetable, so book ahead in summer and at weekends and plan your day around the last boat back. From the pier or the village, Knockmore is a walk – there’s no vehicle access to the summit, and nothing to pay: the hill is open, free and unstaffed all year.
Walking to the summit
There’s more than one way up, and none of it is technical – this is a hill walk on heather and peat rather than rock. The gentler line comes up the southern slopes from near the village: easy-angled ground rising to a broad top of peat hags, quiet, with Clew Bay open the whole way. A steeper start from the north-west flank climbs a grassier ridge and brings Croagh Patrick and the Mayo mainland into view as you gain height.
Either way, don’t treat the paths as a marked trail. Bring a map or an offline GPS track, because the ground is featureless in cloud and the top is a wide plateau rather than an obvious peak. The summit cairn is the one clear landmark, and a decent spot to sit out of the wind.
Landscape & Wildlife
Knockmore’s geology is a mix of psammitic and semi-pelitic schists from the Sraheens Lough Formation, with limestone outcrops along the western cliffs. The upper slopes are characterised by peat hags – irregular, mushroom-shaped peat formations that give the hill a distinctive, weathered texture. The surrounding grasslands and heath support hardy sheep, while seasonal pools attract frogspawn after rain. Birdwatchers often spot meadow pipits, skylarks, and occasional raptors circling the thermal updrafts. The western limestone cliffs are particularly striking in the low light of early morning or late afternoon.
History & Archaeological Connections
While the mountain itself holds no recorded ancient structures, its Gaelic name reflects a long tradition of naming prominent natural features. The wider island is part of the Clew Bay Archaeological Trail, which takes in a 16th-century tower house, a medieval Cistercian abbey, and a Bronze Age court tomb. Many visitors pair the Knockmore ascent with a walk to these sites, tracing how the island’s terrain and its place out in the Atlantic shaped centuries of settlement.
Tips for Visitors
- Footwear: Sturdy walking boots are essential. The peat hags and grassy tracks can be soft and uneven, especially after rain.
- Weather: Atlantic weather changes quickly. Pack a waterproof layer and windproof jacket, even in summer.
- Timing: Start early to avoid midday winds on the summit, and allow time to explore the village or abbey on the way back.
- Navigation: The paths aren’t waymarked, so carry a map or an offline GPS track; mobile signal is patchy on the upper slopes and the top is a broad, featureless plateau in cloud.
- Ferry Note: Return ferry times are fixed. Check the schedule before heading out to ensure you catch the last crossing back to Roonagh.
The mountain isn’t the hard part – the ferry is. Return crossings are fixed and few, so check the timetable first, work out your walk around the last boat, and don’t get so lost in the view from the cairn that you miss it.