The classic short drive from Machynlleth
If you have one morning and want to understand why people drive here, this is the route. North from Machynlleth on the A487 through Corris, 5.6 miles up the valley, past Minffordd and up Bwlch Llyn Bach to the Cross Foxes junction — and back, or round, by the B4405 along the shore of Tal-y-llyn lake beneath the southern wall of Cadair Idris. Visit Wales calls it one of the most spectacular mountain passes in Wales and gives a circular version of about 40 miles by the A487 and A493, roughly an hour and a half before stops.
It is also the least demanding drive here. Both roads are two-way with a white line, so there is no single-track etiquette to learn and no reversing on gradients — the right choice for a nervous driver, a large vehicle or a first day in the area.
Bwlch Llyn Bach, and the fault that made it
The A487 climbs to a summit given as about 285 metres, and the reason the valley below looks so improbably straight is geological. Tal-y-llyn sits in a trench following the Bala Fault, a major fracture running clear across Wales from the Cheshire border to Tywyn on Cardigan Bay; ice exploited the line of weakness and left the flat-floored, steep-walled corridor you drive through, with Cadair Idris rising in one sweep to 893 metres on the northern side.
The driving is straightforward but not casual. The climb from the Corris side is long and steady, with tightening bends near the top and a real drop on the valley side; coming down towards the lake, use the gears rather than the brakes and expect the view to pull your eye off the road. Water runs across the carriageway after heavy rain and this face holds ice. Motorcyclists and cyclists use it heavily in summer, and the laybys are for stopping in, not for lingering half on the carriageway.
The lake, and the road along it
Tal-y-llyn — older Welsh name Llyn Mwyngil — is a stranger thing than it looks: it covers around 220 acres but averages only about eight feet deep, and what dams it is not bedrock but a mass of landslide debris that came down after the glaciers left. The B4405 runs along the shore, and on a still morning the mountain doubles itself in the water. Anglers have known it for generations for wild brown trout, with permits traditionally issued by the Tyn y Cornel Hotel on the shore — though no fishing took place in the 2024 or 2025 seasons because of access difficulties, so check before travelling with a rod.
Near the pass stands Llam y Lladron, the robbers' leap, from which the Red Bandits of Mawddwy were said to have been thrown to their deaths — the same gang who robbed travellers over Bwlch Oerddrws, the other side of the ridge.
Minffordd: the trailhead at the foot of the mountain
Where the B4405 leaves the A487 at the Tal-y-llyn turn is Dôl Idris car park, the start of the Minffordd Path and the best-equipped stopping place on the route. The National Park publishes a daily rate of £6, or £3 for up to four hours, payable by chip and pin or contactless only, with three Blue Badge bays, EV charging, an accessible toilet and a tea room. From Machynlleth it is roughly a 15 to 20 minute drive.
The path itself is a serious mountain route: about 6 miles (9 km) there and back with 788 metres of ascent, graded very strenuous, five to six hours, and not waymarked, so a map and compass are not optional. If nobody wants that, Dôl Idris sits inside Cadair Idris National Nature Reserve and has four short waymarked trails from the car park, two of them accessible.
Abergynolwyn and the Talyllyn Railway
Follow the B4405 west past the lake and it drops down the Dysynni valley to Abergynolwyn, old slate country and a Talyllyn Railway station. The line opened in 1865 to carry slate and, when closure loomed in 1951, volunteers took it over and ran it themselves, making it the first preserved railway in the world. Trains run more than seven miles from Tywyn Wharf up to Nant Gwernol above Abergynolwyn, about an hour each way.
For a driver this is the useful bit: Abergynolwyn station has its own car park, listed at around £1 a day, with a tea room, the Quarryman's Caban, open when trains are running. Dolgoch Falls station has pay and display at about £2 and access to the ravine walks past the falls. Between them you can leave the car, ride a stretch of the line and walk back. The railway runs seasonally; a recent adult Explorer ticket was listed at around £22 and a child's at £11, so check timetable and fares.
The Mach Loop question
The laybys on the A487 either side of the pass are also the parking for Cad West and Cad East, two of the best-known Mach Loop aircraft-watching positions on the hillside above. On a promising weekday in the flying season they fill early, and a mid-morning arrival may find nowhere to put the car.
Watching aircraft from the hillside is a different activity from driving the pass, and it has its own pages: Cad West for the layby, the walk up and the honest odds, and Cad East for the morning position on the same slope. If the laybys are full, drive on to Dôl Idris or the lake shore rather than improvising: this is a trunk road on a gradient, and a car protruding into the carriageway is a hazard to traffic that cannot see it.
Practical information
Allow a morning for the pass and the lake, or a full day with the railway or a walk. Fuel is available in Machynlleth and Dolgellau, nowhere on the route. Public transport gets you much of the way: the TrawsCymru T2 runs the A487 through Corris to Dolgellau roughly every two hours and stops at Minffordd, and the G24 calls at Talyllyn Lake and Dolgoch Falls — see getting around.
The A487 appears on the Traffic Wales alerts feed, worth checking in winter; the pass is high and shaded enough to hold ice when the valley does not. Prices and opening times change, so confirm before relying on them, and see our practical driving guide and weather page. The natural next drive from Cross Foxes is east over Bwlch Oerddrws and back down the A470, making a two-pass circuit of the day.
Day trips