Overview
Slemish is the worn-down core of a volcano, a steep craggy plug that stands out sharply above the flat farmland east of Ballymena. At 437 m (1,434 ft) it is the highest thing for miles, and by tradition it’s the hill where a teenage Saint Patrick spent six years as a slave-shepherd. That combination, a short sharp climb and a big story, is why people come.
Be clear that “short” doesn’t mean easy. The round walk is only about 1.5 km (0.9 mi) and takes roughly an hour, but the upper slopes are rocky and involve a bit of scrambling, and there’s no marked path. The reward at the top is a wide view over the Antrim countryside to the Scottish coast, and the Sperrin Mountains on a clear day.
Geology: a volcanic plug
Slemish is the exposed plug of a volcano active around 60 million years ago, in the Palaeogene period, its core made of hard olivine dolerite. The softer rock around it eroded away over millions of years, leaving the steep hill you see today, visible from thirty miles off on a clear day. That resilience is exactly why it survived as a landmark long after the rest of the volcanic system wore flat. Slemish is classed as a Marilyn (a hill with 150 m of prominence) and sits within an Environmentally Sensitive Area.
History: the holy hill of St Patrick
The Irish name, Sliabh Mis, means ‘Mis’s mountain’, a reference older than the Christian era. Tradition holds that a 16-year-old Patrick was seized by raiders, brought to the north-east of Ireland and made to herd sheep on Slemish for a chieftain named Milchu (also given as Miliucc). Through those six solitary years he turned to constant prayer, the awakening that later drove his mission across Ireland. A nearby early-Christian site, Skerry Churchyard, is thought to be one of the first churches he founded on his return. The hill became known as the Holy Hill of St Patrick and is still a place of pilgrimage.
It has had other uses too: during the 1798 rebellion, Slemish was the site of a United Irish camp.
Walking the loop
The lower slopes follow a grassy track; higher up the ground turns rocky and needs light scrambling. There’s no way-marked trail, so walkers pick their own line, with the south-western approach the gentler one.
- Navigation – The free ActiveME app has a GPX/KML file and live map for the loop; a printed map is posted at the car park.
- Dog-friendly – Dogs are welcome but must be kept on a lead near the surrounding farmland and wildlife.
- Facilities – A large free car park, a toilet block, picnic tables and interpretation boards sit at the trailhead. There’s no shop or café, so bring your own food and water.
- Safety – The rock gets very slippery when wet, and the descent is often trickier than the climb. Wear grippy shoes, bring waterproofs, and take your time coming down.
Flora and fauna
The open heath and grassland hold upland birds: wheatears, meadow pipits, buzzards and ravens over the summit, with Irish hares common on the plains below. The sparse ground gives decent wild-flower spotting in late spring.
St Patrick’s Day pilgrimage
The pilgrimage on 17 March draws over a thousand climbers. Since 2025 the event has run a park-and-ride from the Silverwood/Michelin site on Raceview Road, Broughshane (off the M2), with buses from 9am to a last departure at 3.30pm. On-site parking at the base is closed that day; only blue-badge holders and service dogs may use it. There’s a petting farm, face-painting, traditional music and a marquee for dancing, and climbers who reach the top get a certificate (while they last). The rest of the year, local heritage groups run smaller guided walks for a quieter way up.
Practical Information
| Item | Details |
|---|---|
| Length | 1.5 km (0.9 mi) round-trip |
| Estimated time | About 1 hour |
| Elevation gain | 180 m |
| Difficulty | Moderate – steep and rocky |
| Parking | Free car park with toilets and picnic area (restricted on 17 March – use park-and-ride) |
| Admission | Free |
| Dog policy | Dogs allowed on lead |
| Best season | Late spring to early autumn; 17 March for the pilgrimage |
| Navigation | Trail is unmarked; use the ActiveME app or the printed map |
| Facilities | Toilets, picnic tables, interpretation boards |
Getting there
From Ballymena, follow the A42 eastwards for about 8 km, then turn onto the B94 towards Broughshane. Signs for Slemish Mountain appear shortly after the turn, and the car park at the base of the southern slopes is clearly signposted.
Nearby attractions
Once you’re back down, Ballymena has the nearest dining and shopping, and Ballymena Castle is close by. For the coast, head north into the Antrim Coast and Glens, which takes in the Giant’s Causeway and Dunluce Castle.
Safety notes
The route is not wheelchair-accessible and gets hazardous when wet. Stay on the established line, watch for loose stone, and be ready to turn back if the weather closes in. Phone signal can drop out on the summit, so download offline maps before you start.