A Guide to Climbing Corn DU and Pen y Fan Mountains

  • Post category:Wales
  • Post last modified:April 21, 2021
  • Reading time:15 mins read

Lying in the Brecon Beacons National Park mountain range in South Wales, Corn Du and Pen y Fan are its two highest mountains. In fact, they are the highest in southern Britain! Corn Du peaks at 873 metres and Pen y Fan’s summit is 886 metres above sea level. To the east of the Brecon Beacons lies the Black Mountains range, covering approximately 80 square miles between Abergavenny and Hay-on-Wye. Both mountain ranges are geologically important examples of old red sandstone formed around 359 to 416 million years ago and are crucial habitats for various flora and fauna. As such, the Brecon Beacons has been designated as a Special Conservation Area (SAC) and much of the Black Mountains is a Site of Special Scientific Interest (SSSI).

As you would expect, walking along these mountain ridges is one of the most exhilarating and rewarding activities to do in the Brecon Beacons. The scenery as you hike up Corn Du and Pen y Fan is absolutely glorious.

Panoramic views from Pen y Fan peak

On a clear day, you can see vistas over the Severn Estuary, Cambrian Mountains, Black Mountains and counties of Herefordshire, Gloucestershire and Somerset. You may also see evidence of the Bronze Ages as both summits were used as burial places during that time.

How to Climb Corn Du and Pen y Fan

These two mountains are good ‘starter mountains’. If you want to get into climbing mountains as a hobby or even just as a one off and don’t want to go for the toughest climbs,  Corn Du and Pen y Fan give you a good days’ walk, spectacular views and a real sense of achievement. It is 4 miles long to walk the two peaks in a circular way and many children are found scaling the heights too. You could just climb Corn Du and head back down again but although a tough walk at times, it is really worth it to do the two peaks at once. Pen Y Fan peak from Corn Du is only one-third of a mile approximately.

You could even include the third highest peak of the Brecon Beacons, Cribyn at 795 metres, but for many, the two are enough!

Map of Corn Du and Pen Y Fan Climbing Routes

There are many routes up and down the mountains, some harder than others of course. It would be advisable for you to research the exact routes up and down before your climb so you can choose what is best for you and know exactly where you are going on the day. Below is an idea of what the climb would be like.

Pont ar Daf car park for Pen y Fan mountain

Most routes start at the Pont ar Daf car park near the Storey Arms Outdoor Education Centre.

Easier route up to Pen y Fan mountain from Pont ar Daf car park

At the end of the car park, there is a gate leading to a bridge over the river and then onto a footpath you can follow taking you upwards. The footpaths are very well defined and clear to follow. When choosing your route, you may want to take into account how steep you want to climb (either going up or down) and what views you get by doing one over the other. 

A complete video guide to Pen y Fan

Here’s a short video that covers pretty much most things you need to know before climbing Pen y Fan. The video covers maps of parking, climbing routes and panoramic views you will come across.

Climbing Up Corn Du and Pen y Fan

Steeper route up to Corn Du / Pen y Fan from near Storey Arms Outdoor Education Centre

We took the steep route up the mountain because you get such incredible views by doing so.

The weather can change suddenly and it can get very windy

As you climb further up, it suddenly becomes more windy and the mountain edges become even more exposed so watch out!

Corn Du summit – when wind picked up and it was suddenly cloudy. The cliff face looked almost like a mysterious side profile of a human face!
The final stretch – Corn Du summit (876) final climb

Once you reach the summit at Corn Du, this is where you can choose to take on another stretch to Pen y Fan or to come down the mountain.

View of Pen y Fan peak from Corn Du

Once you’ve got this far however, you can see Pen y Fan’s summit, just a third of a mile away and many feel excited to carry on.


After having left the summit of Corn Du behind and heading onwards and upwards to Pen y Fan, you can view some ancient glacial lakes as you look out, including the best kept one in South Wales, Llyn Cwm Llwch.

Lake Llyn cwm Llwch – an ancient glacial lake near Pen y Fan

This sparkling lake is shrouded in mysterious legend as it is said that there is an island inhabited by fairies in the middle of the lake but it is invisible from the shore. Every May Day, the door to the island was opened and the fairies would play music, tell stories and give visitors beautiful flowers and gifts. That is until one May Day, a greedy visitor took a flower from the island, lost all his senses and the door was never opened again! 

View of Cribyn peak from Pen y Fan

When you get to the summit of Pen y Fan, spend some time there, soak in your feeling of accomplishment and enjoy the spectacular vistas.

Pen y Fan summit – The plaque by National Trust at 886m above sea level, making it the highest peak in Southern Britain

The summit can be busy at times, especially when the weather is good, so you may have to wait your turn to get a picture next to the sign of the number of metres you have climbed. But you do want that as a souvenir!

The relatively flat summit at Pen y Fan peak

You can even have your picnic here, sitting on the rocks! The cairns (stacks of rocks) on both summits were once Bronze Age burial chambers where evidence of a bronze brooch and spearhead have been found inside the chamber.


Being at the summit is amazing and humbling in that you are part of ancient history, walking where so many have climbed since prehistoric times whilst being surrounded by mother nature at its best.

Climbing Down Corn Du and Pen y Fan

Route down from Pen y Fan

When you are ready to descend, there is a less steep route down following the ridge to the right. You’ll see more of the old red sandstone following this route. 


The view on your way down is equally as impressive.

Walk back down to Pont ar Daf

Keep following the path and you’ll come back to the bridge and gate leading to the car park.

What Do I Need to Climb Pen y Fan and Corn Du?

Climbing any mountain carries risk due to wild, rocky and often treacherous landscapes so it is important to be prepared for all eventualities. The weather can also change very quickly, even on what may seem to be a calm sunny day, especially as you get closer to the summit. As a minimum, we would recommend you take the following:

  • A large backpack or rucksack that is comfortable to carry all your essentials in.
  • Water and food e.g. a picnic, snacks etc. It isn’t advisable to take fizzy drinks or very sugary food as they do not maintain energy levels well.
  • Map of the area you are walking (gps or paper map with waterproof cover) and a compass.
  • Basic first aid kit.
  • Extra clothing depending on the weather – layers are best as it can get colder towards the summit and at the same time you can feel warm when climbing up.
  • Waterproof jacket and trousers as again, who knows what the weather will be like?
  • Sunglasses, sun hat and sun cream again depending on the weather.
  • Well fitting hiking boots to provide full support.
  • Emergency shelter for example thermal blankets, survival bags, bothy bags etc.
  • Torch (light enough to carry around).
  • Emergency whistle.

It is advisable that you do some research and preparation into the equipment you’ll need before climbing any mountain so you are ready for all situations and are just able to enjoy the climb itself. 

How to get to Corn Du and Pen y Fan and Where to Park

How to get to Corn Du and Pen y Fan by Car

It is best to use the Pont ar Daf car park although bear in mind parking is limited and can be very busy, especially on warm summer days. The postcode to use for Sat Navs for the Pont ar Daf car park and the nearby Storey Arms Outdoor Education Centre is LD3 8NL

How to Get to Corn Du and Pen y Fan by Train

The closest train station is Merthyr Tydfil which is 12 miles away. Abergavenny train station is 30 miles away. From both these stations, you can get the X43 bus which alights at the Storey Arms.

How to Get to Corn Du and Pen y Fan by Bus

The TrawsCymru T4/T14 route from Cardiff to Newtown stops outside the Storey Arms. You can also get the X43 bus from Merthyr Tydfil and Abergavenny train stations (see How to Get to Corn Du and Pen y Fan by Train above).

Please note: there are no toilet or refreshment facilities at the Pont ar Daf car park.        

It is such a joy climbing Corn Du and Pen y Fan. A wonderful day out for all the family! You will experience the challenge of climbing the two highest mountains in Southern Britain, the delight and satisfaction when you reach the top and take in those spectacular views and the myths and legends encompassing the ancient peaks.

Pen y Fan and Corn Du photo gallery

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