NG4092820624 From the car park at the end of the public road, walk through the Glen Brittle campsite, pass left of the toilet block, and take the well-used trail uphill. At a junction go right, cross a burn, and follow the path east-southeast. Cross the Allt Coire Lagan and continue on a rising traverse below the southern flank of Sron na Ciche. Where the path forks stay left, climbing more steeply around the foot of crags to enter the mouth of Coir' a' Ghrunnda.

NG4459219368 Follow the path north-northeast up scree and slabs. As height is gained the trail divides into several sketchy routes crossing a large boulder field, and there's a tendency to drift too far uphill on the left. Above, a slabby wall seems to bar access to the upper corrie. To bypass this, aim just left of the prominent waterfall, and scramble easily up leftwards in an open gully to reach easier ground above. Trend back right, crossing the burn to reach the shore of Loch Coir' a' Ghrunnda, an impressively austere spot cradled beneath the screes, crags and jagged summits of the Cuillin.

NG4524320081 From the inlet at the far end of the loch, don't head direct for the Bealach a' Garbh-choire, but instead go roughly east to locate a well-worn trail up reddish scree. Steep and eroded, but with no real scrambling, the path soon begins to bear right, meeting the north ridge of Sgurr nan Eag near the top. This Munro has several summits: the high point is at the far end, via a nice rocky ridge walk with some limited scrambling.

NG4570719521 Retrace your steps, but then stay with the north ridge down to the Bealach a' Garbh-choire. There's some interesting blocky scrambling on the direct descent (grade 2), while easier scrambling (grade 1) and scree paths can be found just down on the left flank.

NG4542520152 North of the col is the dramatic rock molar of Caisteal a' Garbh-choire. The traverse of this peak will be a roped climb for most teams, so bear right to bypass it on the east flank of the ridge, clambering over boulders of amazing rough peridotite. In poor visibility the easiest route finding is now to scramble up the blocky ridge (grade 2) to Sgurr Dubh an Da Bheinn, but to avoid having to climb this peak twice it's better to bypass it first...

NG4546120269 From the col between Caisteal a' Garbh Choire and Sgurr Dubh an Da Bheinn, follow a vague traverse path rightwards across scree, below crags, to reach a loose gully (grade 2) leading up to the ridge between Sgurr Dubh an Da Bheinn and Sgurr Dubh Mor. Skirt right of some pinnacles of fantastically weathered peridotite to reach the SW flank of Sgurr Dubh Mor. Climb a short gully of shattered basalt, then move right along a path to the foot of a clean slabby corner. Climb this, then follow a worn path up and right. Where this hits steep rock, step left along an exposed foot traverse, then continue on the well-trodden path up and left to reach the airy summit ridge (grade 3). The high point is marked on maps at the near end, but on the ground the further summit looks higher (and it's worth a careful detour anyway).

NG4577620539 Retrace your steps down the zigzagging line of least resistance (probably the most precarious part of the day), then follow the ridge, passing left of the peridotite pinnacles before scrambling (grade 1) up to the summit of Sgurr Dubh an Da Bheinn.

NG4551320460 Go west-northwest down the broad ridge, passing several stone-walled bivvy sites. Cross the Bealach Coir' an Lochain, and start ascending again. Unseen ahead, the infamous TD Gap (Severe) blocks a direct continuation along the main ridge. This route completely bypasses it. On the approach to the TD Gap the ridge rises to a pinnacle; just before this, look for a well-worn line that descends easily left. A clear path now traverses scree immediately below the huge southern wall of the TD Gap and Sgurr Alasdair. Once the cliffs are outflanked, the path climbs up towards the Bealach Sgumain between Sgurr Sgumain and Sgurr Alasdair - a point marked with distinctive gothic pinnacles.

NG4492020695 From the Sgumain Bivy Cave (you can't miss it) climb scree very briefly, then turn right to follow a slightly descending shelf well below the crest of Sgurr Alasdair's southwest ridge. A direct ascent of this ridge via the well-named Bad Step is a nasty pitch that's hard to recommend even to climbers. Here's a bypass: Make for a chimney down on the right. Polished, but with positive holds, this gives a steep ascent at the upper end of grade 3. Above, easier scrambling up broken ground (but with an unthinkable potential fall below) leads up a vague depression to Sgurr Alasdair's airy summit.

NG4500520773 Climbers, particularly if they've brought a rope, might now continue along the main ridge over Sgurr Thearlaich and Sgurr Mhich Choinnich; however, that's harder and more serious than anything hitherto, so here's where this route makes a beeline for home. Descend the airy southeast ridge of Sgurr Alasdair (grade 2) to the tiny col between it and Sgurr Thearlaich. You're now at the head of the Great Stone Chute descent. This starts out as a dramatic narrow scree gully and then opens into a huge scree fan - the operative word here being scree. Keep your helmet on for this appalling descent; in places it's marginally less collapsey on the right flank, but really there's no enjoyable way. Mobile rubble leads right to the floor of Coire Lagan. No doubt thankful for being back on solid ground, pass north of the lochan to pick up the well-trodden path back to Glen Brittle.