Too right: 85ft-high images of abseiling down a sheer cliff or of crossing a bottomless crevasse on a spindly ladder may well bring on vertigo, aural trouble and many other conditions you've never even dreamt of. But that's what makes the film Everest so exciting. It's impossible to ignore pictures seven storeys high. They make for a sky-scraper-sized Boys' Own adventure.
The latest movie to open at London's Trocadero in Piccadilly, the only working Imax cinema in the UK, takes you hiking with an expedition to the top of the world's highest peak. And although you don't have breathing difficulties or summit-fever-induced hallucinations about yetis, you do get that sense which all the best cinema brings: being there. Forget Journey to the Centre of the Earth and Journey to the Bottom of the Sea; Journey to the Top of the World is much more rousing.
When the white boulders of an avalanche tumble down the mountain towards the camera, you find yourself involuntarily diving for cover beneath the cinema seat in front. It is all too easy to see why one-third of the 158 fatalities on Everest have been down to avalanches.
Meanwhile, as a white-out descends without warning, you can almost feel the wind-chill factor of minus 100 degrees that caused one mountaineer to crack her ribs in a coughing fit, and another to lose both his hands and his nose to frostbite. And as the camera peers into a cleft in a glacier apparently without end, you shiver and fully understand the Sherpa saying: "If you fall down a crevasse, you will fall all the way to America." I'm told the Imax film about a roller-coaster in Brussels is just as frightening.
These images were captured on a specially developed camera, able to function in temperatures of minus 40 degrees and fitted with extra-large buttons, so that cameramen could operate it without removing their gloves and risking losing fingers. Its weight was reduced from 40kg to 22kg; light loads are so crucial on high-altitude climbs that mountaineers cut their toothbrushes in half.
As if the very grandeur of the mountain didn't make for enough natural drama, the film-makers, led by the experienced American mountaineer David Breashears, encountered further unexpected tragedy when the team climbing ahead of them were caught in a sudden 70mph blizzard near the summit. The film crew listened helplessly on the radio as New Zealander Rob Hall, too weak to move, spoke to his seven-months-pregnant wife back home. Along with seven others in his party, he froze to death on the mountain soon afterwards.
Without sticking its crampons into pretentious territory, the film manages to point up the spiritual side of high-altitude climbing. Jamling Tenzing Norgay, the film crew's climbing leader, is the son of Sherpa Tenzing, who, with Sir Edmund Hillary, was the first to climb Everest. Norgay sees climbing in soulful terms: "Religion plays a big part. Everest is a goddess, so we pray to her before we go on the mountain. She teaches you to respect things and to try not to be who you are not. When you see dead bodies on the summit, it gives you a reminder of how tiny we are in this universe; Everest makes you feel so small. On the mountain, you also learn to work with other people as a team. Those are qualities you need for anything in the world - whether you're working in a hamburger restaurant or up Everest."
"Jamling gave us a link to Buddhism and the reverence and humbleness the Sherpas feel for the mountain," Breashears observes. "They don't have a word in their vocabulary for `conquest'. There's no place in the high mountains for arrogance or hubris. People ask me, `what's the most dangerous thing up there?' thinking I'll say, `avalanches' or `the cold'. But actually it's thinking the wrong way - that can get you into a lot of trouble. We should heed the writing of Alexander Pope: `A little learning is a dangerous thing.'"
Bolstered by Norgay's beliefs, the film crew overcame their reservations about continuing after the deaths, and approached the summit. In the final 3,000ft, known with admirable directness as the "death zone", the air is so thin that you can't eat or sleep. It contains two-thirds less oxygen than air at sea-level. The lead climber, an absurdly macho man called Ed Viesturs, who sees a five-hour bike-ride through the desert as "a warm- up", obviously thought oxygen bottles were for wimps and climbed to the top without using any. Near the peak, which juts into the jet-stream at 29,028 feet, he admitted: "This is what it must feel like to drown."
On the summit itself, Norgay was overcome with emotion. "My tears froze to my cheeks," he recalls. "I took a couple of moments thinking of my father there 43 years earlier. I felt very emotionally and spiritually moved and thanked the mother goddess of earth. Those moments were sacred. I touched my father's soul. I looked up at the sky and imagined my father looking down smiling. He laughed, `You didn't have to come such a long way just to visit me.'"
For all this spirituality, cynics still sneer about climbing Everest. "Who cares?" they carp. "What a waste of time and money." Breashears is well aware of this: "If you use adjectives such as `religious' and `spiritual' to describe high-altitude climbing, you have to be careful you don't sound like an evangelical minister. Sometimes you worry that British people will poke fun at this sort of American enterprise."
But the film's great achievement is to silence all such mocking armchair critics (whose only chance of ascending Everest is when a helicopter shuttle service starts up). Instead, the movie inspires unbridled respect for people who have reached the summit of human endeavour. "I hope people will feel the majesty and unrivalled scale of the Himalayas," says Breashears. "It's marvellous to be able to sit out of harm's way in a climate-controlled, oxygen-rich environment and look at these images. Seeing the clouds and peaks is like being close to God.
"But it's not a film about climbing a mountain; it's a human story. These pictures can make you marvel at the human spirit. Everest has always had a strong hold on the world's imagination; it's a great metaphor for human striving."
In the famous scene at the end of White Heat, the gangster played by James Cagney stands at the top of a burning building and screams: "Made it, Ma - top of the world!" That was just fiction; this has the exhilaration of the real thing.
Everest opens at the Trocadero, Piccadilly Circus, London, W1 (0845 600 0505) on Friday.