Crafted from 2,000 hours of footage shot in 15 countries – not to mention such astonishing documents as the recently restored Epic of Everest, from 1924 – Jennifer Peedom's film is not short on breathtaking spectacle.

Making terrific use of the archive of the appropriately named Canadian production house Sherpas Cinema, Mountain provides a marvellous compendium of the craziest extreme sports on the planet. It really ought to be an Imax exclusive. Mountain bikers power along ledges that a mountain goat might baulk at. Other bikers hurtle off precipices and activate parachutes with no seconds to spare. Heli-skiers and snowboarders are dumped from helicopters into avalanches.Base jumpers glide through the air.

Those unfond of vertiginous feats are unlikely to make it past the opening scenes, in which the amazing record-breaking solo climber Alex Honnold smiles down from El Sendero Luminoso, in Mexico. He's 500m up, with no ropes and no harness, just chalk and shoes. What you don't see is the cinematographer Renan Ozturk, himself a climber, swinging around Honnold to get the shot.

There are two stages to the magic of the film: the initial whoa and the follow-up head scratch: how the hell did they film that? And are they still alive? Richard Tognetti's tremendous score, recorded live at Sydney Opera House and performed by the Australian Chamber Orchestra, adds to the goosebumps.

This makes for an interesting dialectic with Peedom's last film, the Bafta-nominated Sherpa, a sharp critique of the Everest industry. Yet, for all its magnificence, Mountain struggles to strike a consistent tone. A bright post-theatrical afterlife in Amsterdam coffee shops and chill-out zones seems assured, but it's never clear if the director is targeting those who want to get high or those who want to get stoned.

Willem Dafoe's stately voiceover, reading text from Robert Macfarlane's Mountains of the Mind, doesn't always sit comfortably alongside extraordinary polyathletic feats. And, at 74 minutes, the film limps towards feature length. Craggy. But worth it for the views.