This is the surface of the world's coolest road. It's 350 miles long, hewn from ice that's 42 inches thick, and is a lifeline for Canada's Barren Lands. The truckers who drive it warn of savage blizzards, blinding white-outs, and temperatures of 55ºC below. They tell us  axles snap like twigs, and bare hands freeze to metal when they touch it. They also tell us not to go there…

Amazing!' I declare for the sixth time today – or perhaps it's the sixth time this half-hour. 'We're driving along a road made of ice!' Surprisingly, nobody in the car clobbers me. My two travelling companions simply nod their heads and continue to gaze out of the windows. We're all alone in the middle of a hundred-mile-long frozen lake and the landscape – flat, treeless, and in multitudinous shades of white – stretches out endlessly in every direction. The scene isn't inspiring much chat; not because it's dull, mind you, but because it's spellbinding. Our frazzled urban eyes are struggling to adjust to such simplicity – no fences, no billboards, no petrol stations, no signs, no telegraph poles. Just nothing for mile after mile. I suppose we could be discussing the morning's drama – watching a freshly shot caribou being gutted and filleted at the roadside by one of our Canadian Indian guides. But then again, welcome to the Barren Lands, where life is harsh and talk is weak.

A sharp crackle from our two-way radio suddenly breaks the silence. 'Six south on 35, all 12 feet wide,' barks a John Wayne sound-alike. I'm already familiar with the code – a convoy of half-a-dozen 18-wheelers is approaching a few miles ahead. We've seen no other traffic all day, so there's no way we're going to miss this photo opportunity. Jumping out of the car onto the ice road is a blast to the senses.

The Range Rover Sport's effortless progress over the glassy surface has so completely fooled my brain's terrain-response system that it fails to engage my feet in 'balance mode', resulting in a wobbly series of steps I dub the drunken moonwalk.

Looking down evokes a dizzy mixture of awe and vertigo as I discover what's thoroughly slippery to the foot is totally gripping to the eye – giant, cracked blocks of turquoise fieldstone up to six feet thick, riddled here and there with ribbons of tiny frozen air bubbles like fibre-optic cables. It's a transparent highway of truly jewel-like beauty. So thick and solid is the surface (yes, I use the scientific method of testing ice mass: jumping up and down on it), it seems more like marble than H2O. Then I get down on my knees to gaze into the depths to see where the ice stops and the dark, unfrozen waters of the lake begin. No sheet of rock could float in this way.

I'm still crouched low when I hear the convoy coming – not from the noise of the approaching truck engines, but from the squeaks of the ice underfoot. The sounds are tame at first, like a Mountie strolling past in a new pair of riding boots, but the noise quickly builds into deafening creaks. Suddenly it's like being below on a sailing ship that's straining hard against a gale-force wind, and as the convoy comes into sight the road begins to shudder, then to rise and fall. Unbelievable – we're surfing on a frozen wave! I have to stretch my arms out wide to keep balance and stay on my feet. I start to panic – is the ice going to crack?