Harold Raeburn soloed this in June 1901, and it still feels like the serious one of the Nevis ridges. It rises straight out of Observatory Gully between Zero Gully and Point Five Gully, and tops out on the plateau within metres of the summit and the ruined observatory — closer to the top than Tower Ridge manages.

Ben Nevis 1345 m, Observatory Ridge

Very Difficult / 400–500 m / ~4 pitches then 250 m+ of grade 3 scrambling / andesite & basaltic lava

Plan

  1. Walk in from the North Face car park to the CIC hut.
  2. Continue south-east past the Douglas Boulder into Observatory Gully to the toe of the ridge.
  3. Pitch the lower four rope-lengths, then move together up the long upper section to the summit plateau.
  4. Descend Coire Leis and rejoin the Allt a’ Mhuilinn path back to the car.

The route

Around four pitches of real rock climbing low down, then at least 250 m of grade 3 scrambling with occasional harder steps to the plateau — that shape is consistent across every account. It is too long to pitch throughout in a September day, so the upper section is moving together or short-pitching.

Both cruxes are turned on the right. The lower pitches weave across slabs and corners as the ridge narrows, and a steep, imposing wall is bypassed on the right in a fine position before regaining the crest. A second tricky pitch higher up, again on the right, overlooks Observatory Gully. No source publishes a pitch-level technical grade for either.

Dry rock is a requirement, not a preference. The lower section is slabby and friction-dependent, and being less travelled than Tower Ridge it stays greasy: “the rock becomes extremely slippy and greasy when wet, so this is a route best tackled in dry weather” (Lochaber Guides). The Highland Mountain Company put it more plainly — “you really need the rock to be dry on this ridge, as there are quite a few slabby footholds that do require a bit of friction in the lower sections.” The north face needs a few settled dry days to come into condition at all.

The rock is andesite and basaltic lava, not granite — the granite on Ben Nevis is elsewhere on the mountain, not in these cliffs.

How it compares

Ridge Grade Length
Tower Ridge Difficult ~600 m
North East Buttress Very Difficult ~400 m
Observatory Ridge Very Difficult 400–500 m

Commitment

  • No abseil is published anywhere on the route, and no escape line.
  • No fixed gear.
  • Loose rock on the ridge needs care, and it is greasier than Tower Ridge when damp.

Logistics

Approach

  • North Face car park → CIC hut (680 m) up the Allt a’ Mhuilinn, roughly 5–5.4 km. Published times run from 1 h 20 with a light sack to over 2 h with a climbing sack.
  • From the hut, head south-east past the Douglas Boulder (the foot of Tower Ridge) and up into Observatory Gully to the toe of the ridge. No reliable published time for this leg — budget generously, and expect old snow: the upper reaches of Observatory Gully hold snow into September most years.

Timing

Guides meet clients at the North Face car park at 07:00–07:30 for this route. Around 10–11 hours car to car is the figure that circulates, though nothing authoritative is published.