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 only direct 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 up to 200 m deep by ice grinding through the Bluestack Mountains during the last Ice Age. 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. The pass tops out at a modest 117 m, so 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; the Geological Survey lists it as a County Geological Site.
There’s a lay-by with a viewpoint and picnic tables roughly halfway through, and it’s the only sensible place to stop. The N15 is a fast national road, and pulling in anywhere else isn’t worth your bonnet.
If you brake for one thing, make it Biddy’s
Biddy’s O’Barnes sits on the Donegal Town side of the pass: a roadside pub with a century behind it, a beer garden, regular live music and a fairly bold claim to the best pint of Guinness in Donegal. For a lot of people it, rather than the scenery, is the reason to slow down, and on a wet day it’s the better call anyway.
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. Stone bridges and the old track-bed ledge cut into the hillside still trace the route.
That track-bed may get a second life. A Barnesmore Gap Greenway is in the works, pitched as a traffic-free walking and cycling route and, as of mid-2025, floated as possibly open within five years. Treat it as a plan rather than a path for now – there’s nothing to cycle yet.
Before you go
The gap is open at all hours, free, and the lay-by parking is free too. Winter is the honest caveat: snow and ice settle on the N15 here, and a dry spring brings its own risk – a large wildfire took hold in the gap in April 2025. Check conditions before you travel, keep to the lay-by when you stop, and don’t count on a toilet unless you’re buying something in Biddy’s.