The Brecon Beacons National Park (Bannau Brycheiniog) boasts some of the most impressive mountain walking in the whole of the UK. One of the best routes in the national park has to be the Blaen-y-Glyn and Fan y Big Walk that I’ll share in this guide.
As an outdoors lover, the 13-km circular walk has everything you want on a hike. It includes the powerful Blaen-y-Glyn waterfall, several epic ridgelines with stunning views and, of course, a summit of one of the funniest-named mountains in the world: Fan y Big.
It’s a challenging half-day hike that should take you around 6 h to complete. There are a couple of steep climbs and you’ll gain a total elevation of 550 m. The challenge is worth it as this lesser-known route doesn’t attract crowds like the main peaks in Brecon Beacons do.
Where to park for this Fan y Big walk
There are a few parking options for the Blaen-y-Glyn and Fan y Big circular walk. Where you park will determine your start and end point for this hike.
We parked at Blaen y Glyn Uchaf. This is the upper car park of the two Blaen y glyn car parks. The second and lower car park is Blaen y Glyn Isaf a few hundred metres away downhill.
The car parks can fill quickly when the weather is good. We noticed that people were using the sides of the main road (which you come off to enter the car parks) as parking areas too. Although I don’t recommend this, if it’s a busy day you may have to consider it, as long as you don’t block passage.
Route for the Blaen-y-Glyn and Fan y Big walk
- Distance: 13 km
- Duration: 6 h
- Difficulty: hard
- Elevation gain: 550 m
- Summits: Fan y Big
The circular walk start point and the end point of the walk is the Blaen-y-Glyn car park of your choice. The terrain includes gravel path, dirt trail, grassy path and a river crossing. The ascents are mostly gradual with a couple of steep climbs which are tough.
Being a circular route, you can tackle it clockwise or anticlockwise. I recommend going anticlockwise for two reasons. The first is that you come to Blaen-y-Glyn waterfall sooner. The second is that if you go in the opposite direction, you’re immediately confronted by a long, steep and tiring ascent to Graig Fan Ddu ridge.
If you want a challenge early on, then go clockwise. But whichever direction you choose, you’ll have the best time and great views.
Blaen y Glyn Uchaf car park
Leave Blaen y Glyn Uchaf car park via the entrance and head left past the signboard onto a well-made path. You’ll descend into a forest and shortly the path will bend left through the trees.
You can stick to this path to drop down to Blaen y Glyn waterfall. Or you can take a dirt trail (that isn’t an obvious path) forking right from the current path as you begin bending left.
This path is uneven underfoot and steep. But I recommend leaving the easier path as this one takes you via another waterfall before you get to Blaen-y-Glyn.
Blaen y Glyn waterfalls
If you take the right fork that I just mentioned, then Blaen-y-Glyn will be the second epic waterfall you see on the hike. The first waterfall is the taller of the two. But Blaen-y-Glyn is wider and more powerful looking.
Instead of crossing the wooden bridge at the mouth of Blaen-y-Glyn waterfall to continue on the route, we got back on the trail to the left of the beautiful waterfalls and headed uphill through the woods.
Don’t do this; cross the wooden bridge to get to the other side of the river. If you make the same mistake as us, and you get back on the trail you came via, you’ll have to cross the river by walking through it.
It’s only shin-deep, but this means you’ll have to remove your shoes. There is a clear crossing point and you access it by hopping a style. However, the river crossing is close to the edge of the falls, which you’re now above—so be careful.
Following the river
After you cross the river to the far bank, you’ll follow the river for a while. This is well and truly bog land and the trail is narrow, so watch the underfoot, tread carefully and prepare to get your shoes muddy. Hug the river as it winds up the narrow valley passing a couple of quaint waterfalls.
After a while you’ll come to a fence with a style. Your only option is to bear right after crossing the style. You’ll ascend from the river, which itself is hidden in a gully, to an open plain.
Look ahead and you see the horseshoe-shaped valley formed by glacial activity. The next stage of the route is to climb to the top of the valley. Head to the ridge immediately ahead of you. There’s no trail here as you cross the plain gradually ascending.
The steep climb
The climb to the top of the valley ridge is the steepest and most challenging part of this fan y Big walk. You’ll do well to climb it without taking a break. I recommend stopping to catch your breath, though, as the views are class.
Atop the ridge the terrain flattens. You’ll see a trig point and beyond that in the distance the Sugar Loaf. You’re treated to panoramic views which make the steep climb worth it.
Wellington bomber war memorial
The next feature on your route to Fan y Big is a WW2 memorial. As you head towards Fan y Big along the ridge, you’ll need to drop down a few metres. There’s a steep trail down to the memorial which you can see below you.
The memorial commemorates 5 Canadian crew members of a Wellington Bomber. The plane crashed at the site in 1942 while on a training mission killing all on board. There are two small piles of wreckage that you can touch (respectfully). It’s an interesting but sombre reminder of the past.
Despite the site being a memorial, you can’t help but enjoy the wonderful views.
Continue on the trail and briefly join Graig fan Las before bearing right towards Bwlch y Ddwyallt a short distance away.
Bwlch y Ddwyallt
A bit of a mouthful, Bwlch y Ddwyallt is the highest point of the plateau atop Waun Rydd mountain. Here you’ll enjoy the most spectacular views of this Fan y Big walk.
As the trail snakes around Waun Rydd, the summit of Pen y Fan, the highest peak in the Brecon Beacons National Park, comes into view. Corn Ddu, Cribyn and Fan y Big all align creating an amazing photo opportunity
We stopped to eat at Bwlch y Ddwyallt. In good weather you can see the Bristol Channel and the west coast of England in the opposite direction to Fan y Big.
Craig Cwareli
From Bwlch y Ddwyallt you can clearly see how the trail follows the landscape down to the summit of Fan y Big. This section is called Craig Cwareli and it’s an intersection of trails. There are gorgeous views from here.
Fan y Big
You’ll probably find lots of people at the top of Fan y Big (unless you do the hike early). This isn’t too bad though as up until now the route will likely be quiet.
Along with its hilarious name, Fan y Big is popular because of the ‘diving board’.
The diving board
At the top of Fan y Big is a flat rock extending over the cliff edge. This is the diving board and it’s the picture that everyone who climbs Fan y Big takes. The summit of Cribyn, and Pen y Fan and Corn Ddu, are behind you and it just looks epic!
Take in the surroundings, get your picture at the diving board and enjoy the namesake mountain. Next up you’ll be heading back along Craig Cwareli the way you came and then bearing right to join Gwaun Cerrig Llwydion plateau.
Gwaun Cerrig Llwydion plateau brings you to Graig Fan Las.
Graig Fan Las
Graig Fan Las is another of the long ridgelines in the Brecon Beacons National Park created by glaciers. The best views of it are from the first ridge which you walk along before you come to the Wellington crash memorial site.
Craig y Fan Ddu
Bear right along Graig Fan Las and it eventually becomes Craig y Fan Ddu ridge. This is the final ridge of the Fan y Big walk.
Walk the length of the ridge before beginning the steep descent to return to Blaen-y-Glyn Uchaf. It’s a steep hill with stone steps that’s hard on the knees, so take it easy.
More adventure travel inspiration on A World Over
This Fan y Big walk is truly an epic one with arguably the best views in the entire Brecon Beacons National Park. So, do yourself a favour and plan it to avoid poor weather conditions.
If you want more adventure travel advice for South Wales, then check out the A World Over blog. I’ve also got a guide to the Pen y Fan horseshoe hike and the Dragon’s Back Brecon Beacons walk.