Ireland’s highest sea cliffs are not at Slieve League or the Cliffs of Moher. They are here, on the empty north-western shoulder of Achill Island, where Croaghaun Mountain drops 688 m (2,257 ft) straight into the Atlantic – three times the height of Moher and almost 90 m higher than Slieve League. They are also the third highest in Europe, after Hornelen in Norway and Cape Enniberg in the Faroes.
Here is the catch, and the reason hardly anyone has heard of them: you cannot see the cliffs from the road, the car park, or the beach. The cliff face is on the far side of the mountain. To see it you either hike to the summit or go out by boat. So treat this as a hill walk, not a viewpoint – and if a strenuous climb isn’t on the cards, Keem Bay at the foot of the trail is a glorious reward in its own right.
The hike
The walk starts from the Keem Bay car park at the western end of the island. The straightforward Keem route is about 5 km return and takes two to three hours; the full loop around to Achill Head and over the summit via Lough Acorrymore is closer to 9–10 km and 4–6 hours. The terrain is open, unmarked, boggy after rain, and very steep in three sustained sections. This is a walk for people comfortable with a map and compass, not a casual stroll.
From the car park the path climbs across heather and rough grass to a ridge above the bay, where the 19th-century coastguard ruins make a useful shelter stop and give the first real sense of scale – golden sand on one side, a sheer Atlantic drop on the other. The route then skirts the lower Benmore Cliffs before the final pull to the cliff edge and the summit, where the ground falls away with no railing of any kind. Wind picks up sharply up here; stay well back from the edge.
The reward at the top is the view the cliffs hide from everyone below: the sheer northern face, the corrie lakes in the bowl beneath, and a sweep east to Saddle Head, Slievemore and Blacksod Bay.
A working coast, not a tourist one
The cliffs have none of the boardwalks, berms or visitor centres of Moher or Slieve League, and that is much of the appeal. The stone ruins on the ridge were coastguard watchpoints built in the mid-1800s to monitor Atlantic shipping and customs, and a Second World War lookout post was added at Moytoge Head above Keem as part of Ireland’s neutral coast watch.
There’s a quieter footnote on the trail too: the ruins of a house once occupied by Captain Charles Boycott, the land agent whose treatment by his tenants in Mayo in 1880 gave the English language the word ‘boycott’. He farmed at Keem before he became infamous further south at Lough Mask.
Wildlife
Two families of peregrine falcons nest on the cliffs; September and October are the best months to see them, when the young are learning to fly. Offshore, Keem Bay is one of the more reliable spots in Ireland for basking sharks from late spring to early autumn, drawn in by plankton blooms, and bottlenose dolphins and porpoises are regular; orcas and humpback whales have been recorded. The cliff ledges hold fulmars, kittiwakes and gulls.
Below the summit sit the glacial corrie lakes, including Bunnafreva Lough West – at over 300 m, the highest corrie lake in Ireland – cupped in a hollow with the sea on the far rim.
Geology
The rock is the Keem Conglomerate Formation, a hard quartz-pebble conglomerate and schist laid down in the late Neoproterozoic (roughly 750–600 million years ago). Its toughness is why the faces stand so sheer. Ice-age glaciers gouged out the valley that now holds Keem Bay and the corries, leaving the resistant sea cliffs behind.
Getting there and practicalities
By car: Achill is joined to the mainland by the Michael Davitt Bridge on the N59. From the bridge, follow the R319 west through Keel to the Keem Bay road, roughly 30 km. The final descent to Keem is narrow, steep and winding – take it slowly.
By bus: there’s no direct service to Keem. Bus Éireann routes 440/450 run from Achill Sound to Dooagh; from Dooagh it’s about a 4.7 km walk to the Keem car park.
Parking: the Keem car parks (lower and upper) fill early on fine weekends and in summer. Come mid-morning at the latest.
Conditions: strenuous and exposed, with cliff-edge sections and no railings. Cloud can drop fast and kill visibility; carry a map and compass and don’t rely on mobile signal up top. Best done late May to early October; winter brings high wind, rain and ice on the exposed ground.
Facilities: a public toilet sits above the Keem car park. There’s nothing on the trail itself – no shop, café or water – so bring your own. Keem is lifeguarded in summer for swimmers, separate from the hike.
Dogs and access: dogs on a lead in summer when the beach is busy. The route is not suitable for wheelchairs or pushchairs. There’s no charge for the cliffs, the trail or parking.
Start early to beat the midday cloud, pack a windproof layer whatever the forecast says, and save energy for the descent – tired legs on wet, steep grass above a 688 m drop are exactly where care matters most.