The ridge linking the four table-top peaks traversed on this walk (Corn Du, Pen y Fan, Cribyn, Fan y Big) forms the majestic core of the Central Brecon Beacons and contains the three highest tops in South Wales. As a result, this classic horseshoe walk around a steep sided glacial valley is amongst the best ridge walks in South Britain, featuring some spectacular views in all directions in good weather.
From a remote reservoir north of Merthyr Tydfil you climb steeply to reach the ridge, from where the gradient is mostly fairly gentle over good engineered paths as you follow a sequence of steep escarpments to Corn Du and Pen y Fan. Pen y Fan is the southern-most mountain in Britain and a large glacial grassy mound with steep glacial sides.
Continuing along the ridge up to Cribyn (which requires a steep ascent and descent, but it can easily be circumvented).
Descent to a col, and either take a good gently downhill track back to the start, or make a final ascent to Fan y Big to complete the horsehoe. An out-and-back extension further along the fairly level ridge – to Waun Rydd alongside an upland bog – offers more superb views, lastly along the Usk Valley.
Route finding is easy (in clear weather), as the whole of the horseshoe route is visible at all times. Despite some steep drops this walk is not scary or dangerous, but it is exceptionally exposed to the elements.
As the horseshoe walk starts from a remote car park, 8 more accessible ascents to the ridge are described.
Note: Corn Du and Pen y Fan are very popular peaks as they can be (relatively) easily accessed from car parks on the A470. Expect lots of walkers (experienced and not) on that short stretch, in any weather.