The pass of the cross
Bwlch y Groes — the pass of the cross — carries a minor road over the shoulder of the Aran ridge between Dinas Mawddwy and Llanuwchllyn, with a third branch dropping east to Llyn Efyrnwy. It is one of the highest public road mountain passes in Wales: sources give the summit as 545 metres, or 1,788 feet, and disagree over whether it or the Gospel Pass in the Black Mountains is the highest of all. What matters more is that this is a lane rather than a highway: two cars wide in places, one car wide in others, unfenced across the top.
The name comes from a cross standing just below the summit, at the junction of the roads from Vyrnwy and Dinas Mawddwy, marking the pass on an old pilgrim route through north Wales. Dinas Mawddwy, at the southern foot, is about ten miles from Machynlleth by the A470 and on the number 36 bus route via Cemmaes; from there the road turns up the Dyfi through Llanymawddwy, and the tarmac narrows as the walls close in.
The climb from Llanymawddwy
This is the side to respect. Visit Mid Wales describes the southern ascent as having severe gradients throughout with a steepest pitch of 1 in 4, and gives it as a remorseless climb of about 350 metres in a little over two miles. One in four is 25 per cent, steeper than almost anything on the ordinary road network, and it comes in long sustained pulls with tight bends where the road doubles back to gain height.
In practical terms: choose a low gear at the bottom and stay in it, because a hill start on a 1 in 4 single-track bend with a car behind you is genuinely unpleasant. Coming down, let the gears and the engine hold the car rather than riding the brakes for two miles, and watch for water crossing the road after rain and loose grit washed into the inside of the bends. There is no barrier for most of it, and the drop off the outside edge is real.
Why to leave the caravan behind
A 1 in 4 gradient on single-track road with hairpins and no run-off is no place for a towed caravan, a large motorhome or a long wheelbase van. The problems compound: a heavy outfit may not restart on the gradient if it stops for oncoming traffic, a long vehicle cannot get round a tight hairpin without using both sides of the road, and reversing an outfit downhill to a passing place in mist is beyond most drivers. Brake fade on the descent arrives without warning.
The alternative is no hardship. The A470 through Mallwyd and over Bwlch Oerddrws is a two-way trunk road reaching the same part of Wales. If you are unsure about your vehicle, drive as far as Llanymawddwy, look at the road, and decide there.
The summit, and where it is safe to stop
Stopping is the point of the drive, and it has to be done deliberately. There is space to pull well clear of the carriageway at the summit, and again at the junction below it where the Vyrnwy road branches. Those are the places to get out, find the cross and take in a view down two valleys at once. Everywhere else, a passing place is not a parking place: blocking one here can strand a farm vehicle for a long way.
At the top you are on open mountain. Sheep wander across unfenced, the wind is stronger than in the valley, and cloud can sit on the pass while Dinas Mawddwy is in sunshine. There is no toilet, no shelter and no dependable phone signal. Walkers use the summit to start on the Aran ridge, and Cwm Cywarch gives the other way onto the same hills, so expect people on the verges as well as livestock.
North to Llanuwchllyn and Bala
The northern descent runs down Cwm Cynllwyd to Llanuwchllyn at the head of Llyn Tegid, steep in its own right and with the same single-track sections. Llanuwchllyn is the southern terminus of the Bala Lake Railway, whose narrow gauge steam trains make a nine-mile return journey along the lake shore to Bala; the trust is raising funds under its Red Dragon Project to extend the line into Bala town. Times and season vary.
From Llanuwchllyn the A494 reaches Bala without further drama, and returning to Machynlleth over Bwlch Oerddrws and the A470 makes a circuit of the day — better than climbing back over the pass.
East to Llyn Efyrnwy
The other descent is the quieter one and, for many people, the better half of the drive: from the junction below the summit the road turns east and drops through the Eunant valley to the head of Llyn Efyrnwy, or Lake Vyrnwy. The reservoir was built by Liverpool Corporation Waterworks between 1881 and 1888, its slate dam 44 metres high and 358 metres long, and it has supplied Liverpool with drinking water since 1891; building it flooded the village of Llanwddyn. The B4393 follows almost all of the lake's 12-mile perimeter.
The RSPB manages around 5,000 hectares of the estate as a nature reserve of moorland, ancient oak and birch woodland and one of the largest areas of blanket bog in Wales. Entry is free and open all year, though charges apply at some of the Hafren Dyfrdwy car parks, where the toilets are.
Sharing the road, and getting home
Bwlch y Groes is a famous climb among cyclists and a favourite with motorcyclists, and on any decent weekend you will meet both. A rider grinding up a 1 in 4 gradient cannot easily stop or move sideways, so give them the whole of your side of the road and wait for a straight stretch rather than squeezing past on a bend. Walkers often have nowhere to step but the ditch, and tractors and livestock trailers use these lanes to get to work: if one appears behind you, find the next safe place and let it through.
Fuel, food and toilets are valley matters — fill up in Machynlleth, Dolgellau or Bala, because there is nothing between. Meirion Mill at Dinas Mawddwy, signed off the A470, has a shop and coffee shop with level access and a disabled toilet, listing opening daily from 10am to 4pm. In winter Cyngor Gwynedd treats its priority routes first and other roads only afterwards, so the pass can be impassable while the valleys are clear. If in doubt take the Tal-y-llyn pass instead, and see our practical driving guide.
Day trips