Franco Cookson makes first ascent of The Dewin Stone, 9a+ slab at Twll Mawr in North Wales

British climber Franco Cookson has made the first ascent of The Dewin Stone, a 9a+ slab at Twll Mawr in the Dinorwig slate quarries above Llanberis in North Wales.
1 / 2
Franco Cookson making first ascent of The Dewin Stone (9a+) at Twll Mawr above Llanberis in North Wales
Franco Cookson archive

Britain's Franco Cookson has made the first ascent of a longstanding project in Twll Mawr, the gigantic hole in the Dinorwig slate quarries above Llanberis in North Wales. Cookson has called the climb The Dewin Stone and proffered the grade of 9a+. As such, it currently stands as one of the hardest slab climbs worldwide.

The route tackles a line immediately to the left of James McHaffie's 9a slab testpiece Meltdown, and shares the crux sequence after having climbed a much harder direct start and before ending with a more difficult independent finish. The crux is comprised of 12 hard moves before reaching Meltdown, and Cookson fell here dozens of times. After tackling the famous Meltdown crux, instead of returning rightwards it continues direct past a further 17 hard moves. The result, in Cookson's words is "41 hand moves (and more importantly, absolutely tonnes of foot moves). The line maybe sounds convoluted, but it's a straight up, following a groove: a brilliant feature, especially for the grade."

Cookson worked out the individual the moves relatively quickly after repeating Meltdown in 2022, but hadn't appreciated the line's intensity. On his Instagram handle after the ascent he admitted "I felt like I was using a totally different energy system on this to when I did meltdown - I was just totally destroyed by the end, power screaming a summoning everything I had."

9a+ slab is a rare phenomenon, with only Disbelief put up by Adam Ondra in 2018 at Acephale in Canada and Cryptography climbed by Alessandro Zeni in 2020 at Saint Loup in Switzerland being half a grade harder. While both Ondra and Zeni have a track record of hard repeats and first ascents, Cookson has at present "only" climbed one 9a, namely Meltdown. Time will tell if The Dewin Stone really is as hard as originally suggested - the same holds true for Disbelief and Cryptography for that matter - but in the meantime kudos to Cookson for this magnificent new addition to the wonderful art of Llanberis slate.

Related crags




Related news
Latest news


Expo / News


Expo / Products
Hooded down jacket designed for high-altitude mountaineering.
A belay device with manual braking, especially designed for crag climbing.
Lightweight, comfortable and ventilated climbing helmet
Merino Wool Ice Climbing Socks, reinforced on the toe and heel.
This very light hybrid fleece (286 g) provides proficient thermal protection to fast ski tourers thanks to its specific construction.
Scott skis, light enough for ski touring, and shaped for freeride skiing.
Show products