Overview
The Slieve Blooms are an ancient, worn-down range. Hundreds of millions of years of erosion have rounded them into the low plateau you see today, and that long history, more than any drama in the skyline, is the character of the place. The range straddles County Laois and County Offaly, rising from the central plain as blanket bog, heath and pockets of conifer and native woodland, a quiet refuge for walkers and wildlife.
The highest point, Arderin (527m / 1,729ft), is a broad bog-covered summit with views on a clear day to the Wicklow Mountains, the Dublin skyline and the Galtees. Use the area’s walking guide to choose a signed forest or valley loop, or plan a longer outing on the Slieve Bloom Way. Exposed ridges, bog and steep sections take more time than the distances suggest, and the ground stays waterlogged long after rain.
History and legend
The Slieve Blooms formed hundreds of millions of years ago, and erosion stripped away the towering peaks, leaving the weathered, rounded profile of today.
The range marked the northern boundary of the ancient kingdom of Osraige, and later Upper Ossory. Mythology runs through the hills: legend has Fionn Mac Cumhaill raised on these slopes by his aunts, Bodhmall and Liath Luachra, who taught him a warrior’s skills, and a cave linked to his boyhood is still pointed out locally. The name Sliabh Bladhma derives from Bladma, a mythic figure of the old tales. Ring forts, megalithic tombs and stone alignments scattered across the uplands show continuous human presence from the Neolithic on.
Walking and hiking
Pick a route before you drive, and allow enough daylight for your return.
- Glenbarrow Eco Walk. Follow the signed route to woodland, the Barrow and the falls. Keep back from wet rock and fast water.
- Slieve Bloom Way. Sport Ireland lists a strenuous circuit of about 70 km. Dogs are prohibited and a longer signed diversion applies when the Ridge of Capard closes. Its notice gives about 74 km with that diversion. Use the current route guide and map and follow the signs on the day.
- Arderin. A separate upland outing. Take a map and compass and turn back if low cloud makes the way hard to follow. The top is marked by a modest cairn and an Ordnance Survey pin.
- Kinnitty and Clonaslee. Forest and valley loops start from these villages and other trailheads; the walking guide lists the current signed routes.
Check individual trail notices for closures and dog rules before setting out.
Nature and wildlife
Much of the upland is the Slieve Bloom Mountains Nature Reserve, a Ramsar wetland and a Special Area of Conservation and Special Protection Area. The blanket-bog ecosystem is the defining feature: sphagnum moss, sundews and heather on the plateaus, with oak and birch in the sheltered valleys. It supports upland birds such as hen harrier, red grouse, merlin, peregrine falcon, golden plover and curlew. Spring and early summer bring heather in flower and the most bird activity; late autumn often clears the air for the longest views.
Getting there and transport
The mountains are best reached by car. The R422 (Rosenallis to Clonaslee) and the R440 (towards Kinnitty) lead to the main trailheads. The nearest service towns are Portlaoise (about 30km north) and Birr (about 25km south). Public transport is limited for direct trail access, so plan how you will reach your chosen trailhead and get back.
Nearby attractions
After a day on the hills, several historic and cultural sites are within easy reach:
- Castle Durrow – An 18th-century estate with formal gardens and guided tours of the demesne.
- Aghaboe Abbey – Atmospheric ruins of a 6th-century monastic settlement in quiet woodland.
- Clonaslee – The main gateway village to the Slieve Bloom Way, with a heritage centre and craft shops.
- Emo Court – A neo-classical mansion and parkland designed by James Gandon.
- Birr Castle – Home to the historic Leviathan telescope and formal gardens, a short drive south in Offaly.
- Clonmacnoise – A UNESCO-listed monastic site on the Shannon, with seven churches, a round tower and royal tombs.
Practical information
- Official website: slievebloom.ie lists trails, maps and notices.
- Admission: free to walk the mountains. Check each trailhead for parking arrangements and notices.
- Trail conditions: these vary seasonally; check the website for path and closure updates.
Tips for visitors
- Weather shifts quickly in the midlands. Pack waterproofs, a warm mid-layer and boots with good grip.
- Boggy sections turn slippery when wet. Trekking poles can help on the approach to Arderin.
- Carry a physical map or a charged phone with offline mapping; the signal can be patchy on the plateau.
- Check dog rules on each trail notice, and keep dogs under control to protect nesting hen harriers and other ground-nesting birds.
- Aim for early morning or late autumn, when the air is clearest and the midland plains show best from the summit.