Ben Oss – Through the Old Pines and Over Beinn Dubhchraig

The walk

The usual way up Ben Oss starts at Dalrigh, south-east of Tyndrum, and goes over Beinn Dubhchraig first. By our map it is about 17.5 km (11 miles) there and back, with about 1,240 metres of climb. Allow about 6 to 8 hours, more with stops, in poor weather or under snow, and leave plenty of daylight for the way down. The summit is 1,030 metres up. It is a long, hard hill day. The lower path is badly eroded and boggy, and three burns are crossed with no bridge. Higher up the ground is rocky, with boulders and scree on the way down to the Bealach Buidhe, and the way is hard to find in mist. The park authority gives the way in outline; no public body publishes a distance or a time for it. Beinn Dubhchraig, 979 metres, is a Munro too, and this walk goes out to its top on the way.

The park authority points walkers to Dalrigh: turn off the A82 at the Dalrigh sign, about a mile before Tyndrum on the road from Glasgow, and keep left for the car park. No keeper publishes its charge or its size. Trains stop at Tyndrum Lower and Citylink coaches at Tyndrum, the authority says, and its directions are a walk of about a mile along the A82 to the Dalrigh turning. By our map the road has no pavement there, and the West Highland Way runs between Tyndrum and Dalrigh off the road. We found no toilets at Dalrigh, so plan for none at the start.

Before you set off, check the mountain forecast, and under snow the snow and avalanche conditions too, as Mountaineering Scotland advises. On the hills it is often much colder and windier than in the glen, even on a clear summer day, Forestry and Land Scotland warns. Wear good walking boots and carry warm, waterproof clothing, plenty of food and drink, and a torch in case the day runs long. Carry a map and compass and know how to use them, and do not rely only on a phone or GPS. Leave word with someone of where you are going and when you will be back.

From the low end of the car park the old road leads south, across the West Highland Way, and over the River Fillan by its bridge. Just beyond, turn right on the track beside the railway. By our map it crosses the railway by a bridge after about a kilometre: go through the gate beyond. A path leads across wet ground to a footbridge over the Allt Gleann Achrioch, about 1.7 km from the car park by our map. One guide found the footbridge in poor repair: cross it with care.

Beyond the footbridge the path heads upstream beside the Allt Coire Dubhchraig, into the pines of Coille Coire Chuilc. The park authority calls these woods one of the last stretches of Caledonian forest, mixed with birch. It can be a wet walk to start with, the park authority warns. The path through the pines is badly eroded in soft peat, and one guide warns you can sink to the knees. It passes old deer fences and leaves the trees for open ground. By our map it then crosses three burns with no bridge, about 3.6 to 3.9 km from the car park. After heavy rain the burns run high, and one guide says to save this walk for a dry spell. If a crossing looks unsafe, turn back.

The path climbs the corrie on the north-east side of Beinn Dubhchraig, steeper near the top, to the ridge north-west of its summit. It reaches the ridge by small lochans, about 900 metres up by our map. Out on the hill there are no waymarks or signposts, and paths can be hard to follow, Forestry and Land Scotland says. Turn left, south-east, along the ridge for the top of Beinn Dubhchraig, about 500 metres on by our map. Then come back the same way to where the path reached the ridge. This is the place to decide. If the cloud is coming down, the wind is rising or anyone is tiring, turn for home: Forestry and Land Scotland asks walkers to turn back if they get tired.

From the ridge the path runs west past the lochans, then drops more steeply through boulders and some scree to the Bealach Buidhe, above Loch Oss. The bealach is about 780 metres up, by our map. On the way down the path passes within about 40 to 60 metres of mapped crags. Do not take the ground down Coire Buidhe from the bealach as a short cut. One guide warns that its rocks are steep and very loose, for competent scramblers only.

From the bealach a fainter path climbs the north-east ridge of Ben Oss: one guide marks where it leaves the main path by a small cairn. The ridges are rocky and uneven, with crags, and in poor visibility the way is hard to find. The path goes over a top on the ridge and down about 20 metres to a small col. From there the summit is about 550 metres on, by our map. It is a cairn on a flattish top of big slabs and grass, with the craggy east face of Ben Lui beyond.

Under snow these are winter mountains, for walkers with winter skills and the gear to match. In winter you need to know the snow conditions and the avalanche risk too, Mountaineering Scotland says. No avalanche forecast covers Ben Oss. The Scottish Avalanche Information Service forecasts six other areas, from Glencoe and Lochaber to the Cairngorms and Torridon, which is no sign there is no risk here.

The owners of the land may be at work managing deer, the park authority warns. Stags may be stalked at any time of year, busiest in the first three weeks of October, and hinds from 21 October to 15 February, Mountaineering Scotland says. Most stalking takes place on weekdays, and often none on a Sunday. Check Heading for the Scottish Hills before you go, and if in doubt keep to the well-known way.

The way down is the way you came, back down the ridge to the Bealach Buidhe. Then climb east again past the lochans to the ridge of Beinn Dubhchraig: about 160 metres of climb by our map, late in a long day. Do not drop north from the bealach. Where the path first reached the ridge, turn left, down the corrie and back through the wood to Dalrigh. In cloud, check the line with your map and compass before you leave each top. In an emergency call 999 and ask for the police, the park authority says. Give your location as exactly as you can, with a grid reference, and the police will send help, which may be a mountain rescue team.