How To Visit Llyn y Fan Fach & Llyn y Fan Fawr – 5 Walking Routes

Llyn y Fan Fach is a glacial lake in the Brecon Beacons. This hiking guide describes 5 walking routes which take in views of this beautiful lake. I provide trail descriptions, distances, times and starting locations.

Picws Du mountain and Llyn y Fan Fach lake

The Black Mountain (singular) refers to a range of mountains in the Western Brecon Beacons National Park. This is not to be confused with the Black Mountains on the Eastern side of the Park.

The highest peak in the Black Mountain (Y Mynydd Du) range is Fan Brycheiniog at 802m. This range of mountains displays breath taking examples of glacially formed cwms (or valleys), lakes and escarpments.

For me this remote western side of the Brecon Beacons offers the best Beacons walking and attracts very view visitors, compared to the Central Beacons and the Black Mountains in the East.

For years locals have revelled in having this glorious spot on their doorstep, but in 2020 popularity boomed after appearing on the BBC’s Secret Britain and being voted the UK’s number 1 Hidden Gem by Hayes and Jarvis.

For information on other top hikes in the Brecon Beacons, click here!

Black Mountain Walks

There are multiple walking routes that allow you to enjoy the Black Mountain range with views of Llyn y Fan Fach and Llyn y Fan Fawr. Below I outline five walks of differing lengths and difficulty that explore this beautifully secluded region.

Before you go:

  • The Llyn y Fan Fach car park near Llanddeusant is remote with no facilities. The final section of road to access this car park is single track with only a few passing places.
  • The layby on Heol Lan is also very secluded with no nearby facilities so make sure you have everything you need before you arrive.

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1. Llyn y Fan Fach Walk 

  • Distance: 8 km 
  • Time: 3 hours
  • Starting Point: Llyn y Fan Fach Car park, Llangadog, Llanddeusant SA19 9UN

From the car park follow the gravel road uphill as it immediately follows the Afon Sawdda river. This is a gradual climb past multiple small waterfalls and cascades, that leads to a beautiful reveal of Llyn y Fan Fach.

Top Tip: If you want an easy Llyn y Fan Fach walk, simply retrace your steps from here and walk back to the car park. This would make a short 4km loop.

After enjoying some time soaking in this great amphitheatre, continue around the lake to the west and ascend the ridge.  The views from the top of this dramatic escarpment are well worth the climb.

Follow the path along the ridge to the north-east, keeping views of the lake down to your left. Climb to Picws Du (Bannau Sir Gaer) which is the second highest peak in this range, before dropping down into the saddle.

At this point bear left down a steep gulley trail which zig zags down the escarpment. Once at the bottom, take the trail to the left to head back in the direction of the lake. Follow the riverside path back down the valley to the car park starting point.

This loop is a great Llyn y Fan Fach short walk which provides incredible views in all directions, however the path down from Picws Du is very steep with some loose scree and exposed edges. This might not be not suitable for small children.

Pro Tip: To extend this walk, rather than turning left down into the gulley, continue up the other side of the saddle onto Fan Foel peak. At the summit cairn, turn left and descend down the shoulder. Continue along the path in a northeasterly direction, as it gradually descends back to the car park. This is my favourite Black Mountain walk since it provides amazing views of both lakes and isn’t as long as some of the other walks. Watch a video of this walk below.

2.  Llyn y Fan Fach and Llyn y Fan Fawr Circular Walk from Llangadog

  • Distance: 15 km
  • Time: 6 hours
  • Starting Point: Llyn y Fan Fach Car park, Llangadog, Llanddeusant SA19 9UN

From the car park follow the gravel road along the Afon Sawdda to reach the first lake of the hike – Llyn y Fan Fach. At this point leave the gravel trail and take the path to the right of the lake to ascend the ridge.

At the top, continue along the ridge path with magnificent views of the lake down to the left. After reaching the high point on this ridge of Picws Du (Bannau Sir Gaer), descend the saddle before climbing steeply back up to the next ridge.

The most northerly point of this peninsula is Fan Foel peak at 781m, which is marked with a cairn. At this point the trail heads in a southerly direction and you can now see the second lake of this hike, Llyn y Fan Fawr. Translating to lake of the big peak, this is one of the largest lakes in Wales.

Views of Llyn y Fan Fach
Looking back towards Picws Du and Llyn y Fan Fach

Continuing along the path you will next reach the highest point on this hike and indeed in this region – Fan Brycheiniog. At this point on clear days, you will be rewarded with fabulous views of the highest peak in the Brecon Beacons, Pen y Fan.

Discover my favourite routes to the summit of Pen y Fan in this guide.

Leaving Fan Brycheiniog, the descent begins. 600m after leaving the peak a path breaks off to the left to steeply descend down to the lake.

Standing above Llyn y Fan Fawr
Walking down the steep path to Llyn y Fan Fawr

Once at the lake, take the path that veers off to the left and circles the eastern (far) side of the lake. Follow this path to the northern end of the lake before taking the path on the left that leads towards to base of the escarpments.

Once on this path simply skirt the ridges that you walked on top of earlier, until you return to Llyn y Fan Fach. From the lake, retrace your steps along the path that returns to the car park.

Not sure how to pronounce all of these Welsh words? Take a look at this post to learn how!

3. Llyn y Fan Fawr and Llyn y Fan Fach Circular Walk from A4067

  • Distance: 20 km
  • Time: 7 – 9 hours
  • Starting Point: Tafarn Y Garreg Pub Car Park

Also known as the Carmarthen fans, this hike starts from a car park next to the Tafarn Y Garreg Pub, on the A4067. This is a full day which, due mostly to the distance, is considered a strenuous walk.

From the car park, cross the road and join the footpath which immediately begins a steep ascent. This fairly quickly becomes a ridge which leads to the first summit of the day, Fan Hir. From here you will get the first views of Llyn y Fan Fawr down below.

Fabulous ridge walking towards Llyn y Fan Fawr
Walking along the ridge to Fan Hir

There is a short descent to the saddle before climbing once again to the top of Fan Brycheiniog. Continue along the ridge a little further to bag the next summit of Fan Foel, after which the trail turns in a westerly direction.

Again there is a small descent to the next saddle before climbing to the summit of Bannau Sir Gaer. Enjoying views now of Llyn y Fan Fach, continue along the ridge to take in the final peak of Waun Lefrith, before beginning the main descent.

Branch off to the right in an easterly direction to walk down to the lake. This is roughly the halfway point and a good place to take a well earned break.

Nick walking beneath the ridges towards the base of Fan Foel

The path now skirts the base of the escarpment as it continues in an easterly direction. After contouring beneath Fan Foel, the trail begins to head south towards Llyn y Fan Fawr.

Walk along the easterly edge of the lake to fully admire the beauty of the lake and then start the gradual descent back towards the car park. There are several pretty little waterfalls to admire as a final reward along the last few kilometers.

4. Fan Brycheiniog and Llyn y Fan Fawr Loop 

  • Distance: 15.6 km
  • Time: 6 – 7 hours
  • Starting Point: Tafarn Y Garreg Pub Car Park

Follow directions for the previous hike to the summit of Fan Foel.  Enjoy views looking down onto Llyn y Fan Fach to the west and Pen y Fan to the  east. From this peak continue along the path in a northerly direction as it descends the shoulder.

Once at the base of Fan Foel, turn right and follow the path back towards Llyn y Fan Fawr. Again walk around the easterly edge of the lake and follow the trail along the gradual descent back to the car park at Tafarn y Garreg.

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5. Short Llyn y Fan Fawr Walk

  • Distance: 10 km
  • Time: 2 – 3 hours
  • Starting Point: Layby on Heol Lan

This walk begins from a layby on Heol Lan road. It’s located 5.5km after turning onto Heol Lan from the A4067. This layby has enough space for just a few cars.

From the layby follow the path to the left. The path to the right heads uphill to a viewpoint which isn’t necessary for this walk. The path skirts around the hill, down into a valley before beginning the gradual climb up towards Llyn y Fan Fawr. 

The path roughly follows a stream most of the way, leading you to the south end of the lake. A loop of the lake is around 2km so this can be added to your walk if you want to enjoy the lake from all sides.

To complete the walk simply retrace your steps back to the layby on Heol Lan.

Sunrise over Llyn y fan Fawr
Llyn y Fan Fawr at sunrise
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Lady of the Lake – The Legend

As with many places in South Wales, Llyn y Fan Fach is steeped in Welsh folklore. According to this legend, a young farmer was grazing his animals when a beautiful lady walked out of the water. He fell instantly in love with her. She agreed to marry him but only on the condition that he must not strike her 3 times.

They were happily married for many years and had 3 sons together. However, as you might imagine this happy story didn’t last. Versions of the myth differ as to the nature of these strikes, but sure enough the farmer did indeed strike his wife e times. On the third occasion, true to her word, she left and vanished back into the cold waters of the lake, leaving the farmer eternally heartbroken.

There are more Welsh folklore tales linked to walks throughout the Brecon Beacons, in particular the walks in Waterfall Country.

What to pack when hiking the Black Mountain

For a complete mountain day packing list take a look at this post, but here are some of the essentials.

Where to stay when exploring the Brecon Beacons

A great central location for exploring the Brecon Beacons National Park is the town of Merthyr Tydfil. Merthyr is perfect for adrenalin junkies as it’s home to the epic Bike Park Wales which is the best place in the UK for mountain biking and close to the newly opened Zipworld.

The Llwyn Onn Guest House is a beautiful guest house on the outskirts of Merthyr, idyllically set right next to Llwyn Onn reservoir. It’s the prefect place to recover from a hike and also just up the road from my mums house!

To discover all the other adventurous activities to enjoy in Merthyr Tydfil and more places to stay, take a look at this post.

Disclaimer: Some links in this article are affiliate links, which means that if you purchase through them I receive a small commission, at no extra cost to you. This helps cover the cost of running this blog. Thanks for your support!

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Walking routes of Llyn y Fan Fach and Llyn y Fan Fawr

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Louise is a tour leader from South Wales who runs adventure tours in Africa, Asia and the Americas. She lives in her converted campervan & is currently based in the UK. Louise is trained in mountain leadership and has a passion for photography.

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