I love the Mournes. This mountain range in the north-east of Ireland is within a couple of hours’ drive from Dublin, which makes it ideal for long day hikes without needing an overnight stay. I’ve written before about Slieve Gullion, the highest point in neighbouring County Armagh. This article focuses on the two highest mountains in County Down — and indeed all of Ulster — and covers everything you need to know about climbing Slieve Donard and Slieve Commedagh.
On my most recent visit, I climbed Slieve Donard and Slieve Commedagh from Newcastle. The route is best thought of as a T-shaped walk: you follow a single path up to a junction, turn one way to summit Donard, return to the saddle, then head in the opposite direction to reach Commedagh before retracing your steps back down.
While this isn’t a looped walk, it’s the most straightforward and practical way to link the two highest peaks in Ulster from the same starting point. The Slieve Donard section of the trail is extremely popular — the Commedagh spur, not so much. However, I think the quieter section really adds to this walk. You will likely have Commedagh all to yourself.
Slieve Donard and Slieve Commedagh Hike Details
Location: Slieve Donard and Slieve Commedagh are located in the Mourne Mountains in County Down. The Mournes contain some of Ireland’s highest mountains. As well as Donard and Commedagh, Slieve Binnian and Slieve Bearnagh also make the 40 highest mountains in Ireland list.
Distance: 12.25km Type of Walk: Out and back from Newcastle to Slieve Donard with a spur to also take in Slieve Commedagh.
Time Required: 4.5 hours. I took a strong pace but did stop for lunch at the summit of Donard.
Elevation Gain: 1,016m. You are starting at sea level from Newcastle – with lovely views out over the Irish Sea. You climb 849m to summit Donard. However, you then have to come down the valley before ascending up Commedagh on the other side.
Difficulty Level: Difficult. You are walking over 12km with significant elevation gain. The final stretch up Donard is particularly steep. You need a good level of fitness for this one. Despite the effort involved, the route itself is easy to follow.
Map of the Slieve Donard and Slieve Commedagh Hike
The below map sets out the 12.25km route.
Other Option
Slieve Donard and Slieve Commedagh Loop: Everyone loves a looped walk. This option takes in the peaks of Donard and Commedagh – see map of the route here. In reality, I wouldn’t recommend this option unless you’re very comfortable with navigation, as large sections have no defined trail and involve difficult terrain. So perhaps more suited to experienced hikers looking for a challenge.
Where to Start the Slieve Donard and Slieve Commedagh Hike
As mentioned above, this route starts from Donard Park car park. Parking is free but can get busy – especially over the weekend. Donard Park is used both by locals with playing pitches and green areas that extend to woodland to the south.
Through Donard Park
Leaving the car park, I followed the line of trees and headed towards the wooded area. I followed the obvious (and well worn) path through the woods. The dappled sunlight filtering through the leaves made this a lovely start to the Slieve Donard and Slieve Commedagh trail.
Along the Glen River
Within the woods, I came across the Glen River for the first time. The waterway runs alongside the Donard trail for much of the route. The first section of the river is probably the most picturesque with lovely stonework bridges, fast moving rapids and even waterfalls to admire.
I crisscrossed the river a few times as I moved steadily uphill. Through gaps in the trees, I now found myself high enough to get nice views out over the sea. Unfortunately, some of these gaps are caused by recent tree felling.
Into more open country
The forest section ended as I passed through a nice wooden gate. Again, looking back offered nice sea views.
With the Glen river now on my left, the treeline continued on my right (for a short while). Past the river, the broad expanse of the mountains stretched out in front of me.
Through the Valley
I could now see the trail in front of me very clearly. The path cut through the basin before rising steeply to the bottom of the U-shaped between Slieve Donard and Slieve Commedagh.
With no navigation difficulties to worry about, I was lucky enough to be able to concentrate on the lovely surroundings.
The Mourne Wall
I reached the T-junction of the trail after just over 4km of walking. I had reached the famous Mourne Walls. Donard rose steeply to my left with Commedagh on my right.
The Mourne Walls are a truly distinctive landmark of the mountain range. Constructed in the 1930’s with the aim of enclosing the Silent Valley Reservoir catchment area, the walls run for an impressive 35km. The walls are to keep sheep and cattle out of the catchment area so they don’t contaminate the reservoir.
To the Summit of Slieve Donard
Turning left at the saddle of the mountains, I headed upwards towards Donard. My pace slowed considerably given the very steep incline. While I was huffing and puffing on my way to the top, several trail runners galloped past me. I always see a lot of trail runners whenever I’m out on the Mournes. It seems to be a very popular place for it.
Eventually, I made it to the top. As I stepped out from behind the protection of the Mourne wall, I felt the full force of the wind. After admiring the views from the top, my next task was to find a side of the slope which was sheltered a bit from the wind. I needed to stop for lunch. I ate my lunch with amazing views out over the Irish Sea. Not a bad reward for the 5km of walking to get to the highest point in Ulster.
Down and Then Up Again
With my sandwiches eaten, I retraced my steps back down Donard. I needed to watch my footing in places to make sure everything felt secure – I really don’t know how those trail runners do it!
While the trail had been quite busy for the Donard section, once I started ascending again towards Commedagh, I had the path to myself.
As mentioned above, I’d recommend Commedagh. I found the solitude lovely and peaceful. I followed the wall up and turned right to get to the high point of Commedagh. It took 7km of walking to get to the second summit.
Back to Newcastle
I simply went back the way I came to complete this great walk. I really enjoyed the return leg as I walked towards the sea to get back to the starting point. This offered up some fantastic views.
I reached the car park tired and weary but really satisfied following a fantastic walk to reach the high point of Ulster. I found the mountain very accessible – of course this meant the trail felt a little busy at times. However, the Commedagh addition offers that peace and serenity side of things. So, If you want to climb Ulster’s highest mountain without it feeling like a procession, adding Slieve Commedagh makes all the difference. You get the iconic summit, the effort, and crucially (to me anyway), some peace and quiet on the way back.
While you’re here on Wild Irish Walks – check out how Donard compares with the high points of the other provinces in Ireland:
- Connacht – Mweelrea
- Leinster – Lugnaquilla
- Munster – Carauntoohil