A pass with a bad reputation
For the best part of two centuries, Barnesmore Gap was the stretch of Donegal you didn’t want to cross alone. The four-kilometre defile carries the road between the north and south of the county, which made it equally useful to travellers and to the highwaymen and rapparees who robbed them – a trade that ran on until about 1800. By the mid-1700s the authorities had posted a garrison of Red Coats at the Ballybofey end and put up a gallows in the pass itself. The Derry Journal of July 1773 recorded the rest of the lesson: two men, Patrick Gordon and Henry O’Neil, were sentenced at Lifford to hang on 8 September at the bridge of Barnesmore – the exact spot where they had robbed a Donegal shopkeeper, James Ferguson.
Today the N15 runs the same line, and the only thing waiting to ambush you is the view.
The gap itself
Barnesmore Gap (Irish An Bearnas Mór, ‘the big gap’) is a glacial valley, just over 4 km long and scoured deep by ice grinding through the Bluestack Mountains during the last Ice Age. Geological Survey Ireland traces the valley along a fault and records deposits left by glacial ice. The granite it cuts through is far older – Devonian, roughly 400 million years. Croaghconnelagh (523 m) rises on the north-west side with Barnesmore Mountain opposite, and the Lowerymore River threads the valley floor on its way to Lough Eske. This is a corridor through the mountains rather than a climb over them. A 17th-century history of Donegal Abbey records the gap as once full of wild red deer, and the Geological Survey lists it as a County Geological Site.
The N15 is a fast national road. Enjoy the view from the road, and stop only where signs permit and you can pull fully clear of traffic.
If you brake for one thing, make it Biddy’s
Biddy’s O’Barnes is a roadside pub on the Donegal Town side of the pass. For a lot of people it, rather than the scenery, is the reason to slow down, and on a wet day it is a fair call. Check its current opening times before you rely on it for food, music or a toilet stop.
The railway, and what might come next
The West Donegal Railway pushed a narrow-gauge line through the gap, opening on 25 April 1882 after seven weeks of snowstorms held up the work. The County Donegal system it became went on to pioneer diesel rail-cars, among the earliest in these islands, before the line closed in 1959. The road, river and former railway still share the valley floor.
That route may get a second life. In August 2026, Donegal County Council published planning and land acquisition applications for a proposed Barnesmore Gap Greenway, a walking and cycling route. Treat it as a plan rather than a path for now, and check the project’s progress before planning a greenway trip. Use signed public routes and keep off the old trackbed.
Before you go
The gap is a public road, and the N15 is busy. Winter is the honest caveat: snow and ice can settle on the road here, so check road and weather conditions before you travel. Keep to places where you can stop safely clear of traffic.