Hardest route up Snowdon
The question has two honest answers — because “hard” means different things to different walkers. The route with the most elevation gain is not the same as the route most walkers find most demanding.
Two kinds of hard
Difficulty on a mountain route comes from two distinct sources — and they point to different routes as the hardest on Snowdon.
Physical difficulty
Total elevation gain, gradient steepness, and terrain underfoot. Measured by how hard your legs and lungs work. The Watkin Path wins here: it starts at just 60 m above sea level and climbs more than 1,000 m to the summit — greater total ascent than any other standard route. Its upper section over loose, steep scree is the most physically demanding of any standard path.
Psychological difficulty
Exposure, ridge-walking, and the vertigo-inducing drops that some walkers find significantly more demanding than physical effort. The Rhyd Ddu Path wins here: its Bwlch Main ridge is a narrow arête with significant drops on both sides. For walkers not comfortable with exposure, this section can feel more challenging than anything on the Watkin Path despite requiring no scrambling.
The Watkin Path — hardest by elevation
Starting at just 60 metres above sea level at Pont Bethania in Nant Gwynant — the lowest trailhead of any Snowdon route — the Watkin Path climbs more than 1,000 metres to the summit. By comparison, the Llanberis Path starts at 100 metres and climbs 975 m; the Pyg Track starts at 359 metres and climbs only 723 m.
The lower section through native oak woodland and past Gladstone Rock is genuinely pleasant. The difficulty begins in earnest above the Cwm Llan slate quarry ruins, where the path transitions to steep, loose scree. The final approach to the ridge is the steepest standard path on any Snowdon route, and the scree becomes treacherous in wet conditions.
The Watkin Path is for experienced walkers only. It is not appropriate for first-time mountain walkers, those in inadequate footwear, or those who do not have navigation competency in the upper section where the path becomes less distinct.
The Rhyd Ddu Path — hardest for those sensitive to exposure
The Rhyd Ddu Path is a hard route made harder for walkers who are not comfortable with heights. After a moorland section that requires active navigation, the path climbs to Bwlch Main — a narrow south ridge with steep ground falling away on both sides. The path is clear and there is no scrambling involved, but the exposure is real and sustained.
Walkers who have done all the eastern routes and want a new challenge often report that Bwlch Main is the most demanding section they have encountered on a standard Snowdon walk. Others who are simply experienced and comfortable with exposure will find it exhilarating rather than frightening.
The honest advice is: if you are the kind of walker who finds the upper Pyg Track zigzags or the Watkin scree demanding but manageable, Rhyd Ddu is an appropriate progression. If you are not sure whether you have a head for heights, do not use this route to find out.