Towers of shattered rock rise around us, wreathed in mist. We’ve been trudging for hours to gain this ridge, only to be buffeted by cold drafts and dampened by the swirling smirr of rain. This is the Black Cuillin of Skye, a ring of mountains forming the crater of an ancient volcano. It’s also the route of the legendary Skye Ridge Traverse, a 12km walk that takes in 11 Munros, the hills in Scotland above 3,000 feet, as originally measured by Sir Hugh Munro in 1891.

The hardest is here is the Inaccessible Pinnacle. A sharp fin of rock rising 50 metres above Sgùrr Dearg, it looked impossible to Munro, who contented himself with the rounded hump below. No such luck for today’s “Munro baggers” who must climb the In Pinn to claim completion.

Most of the Black Cuillin rock is gabbro, a rough grey stuff that tears the skin but grips well. Intersecting it is blocky basalt, with smooth surfaces and a peach hue intensified by orange lichens. These visual charms, however, belie its treachery, for it becomes fiendishly slick when wet. The Inaccessible Pinnacle is basalt too and, when we arrive, is fogged and damp. I love mountains and enjoy a bit of scrambling, but I’m not a climber. I’m also not ticking a list, so I don’t have to do this. But in the company of fine companions, an expert guide and ropes, it feels like a once-in-a-lifetime opportunity.

And – hurrah! – the cloud is lifting. Though this proves to be my undoing. The Pinnacle leans to the right, so while straddling the narrow crest and fumbling for a foothold, I catch sight of the sheer drop plunging thousands of feet below. Panic alarms go off in the brain and stress hormones course through me.

But the only way is up. I clamber on, clinging to that spine of stone for dear life and promising yself I will never, ever, do this again. At the top, I stare out to sea where light spears through cloud to burnish the water. Relief bubbles over into laughter. The abseil down feels comparatively easy and I kiss the sweet earth and thank God I’m alive. As for Munro baggers, I salute you.

• Under the Changing Skies: The Best of the Guardian’s Country Diary, 2018-2024 is published by Guardian Faber; order at guardianbookshop.com and get a 15% discount

• This article was amended on Saturday 11 October to correct the definition of a Munro