The Québec Winter Carnival: The world's biggest winter festival

The cold will set you atremble, and the velocity will make you quake. From up here at the top of Quebec's famous toboggan ride, Au 1884 (named for the year of its birth), the city is a white light at the end of a vertiginous tunnel. Rimming the old city's ramparts like a moat is the St Lawrence River, its frozen surface slashed open periodically to reveal indigo waters. Stretched out along the buried remains of forts and castles left here by the French and British is Dufferin Terrace, sealed in a sheet of ice. And far, far below, at the foot of this precipitous slide, is Fairmont's Château Frontenac, its turrets festooning the skyline like a fairytale.

The operator nudges my toboggan and down I go. The old city flies up to meet me in a blizzard of white. Wind sandpapers my face. Snowflakes prickle my cheeks. The squall stabs my eyes. My heart, left somewhere high above me, jumps back into my chest and flails rabidly as the toboggan grinds to a halt metres from the chateau's front door. The annual Quebec Winter Carnival has begun, and I am its latest initiate.

All through the old city and beyond its ramparts people are defying the coldest seasons and taking to the streets in celebration of this, the world's biggest winter festival. Held annually in the only walled city north of Mexico, the carnival spins enchantment from darkest winter's offerings. Everything is turned to magic – the glacial wind, the gurgling slush, the slippery snowfall. Tobogganers fly down the slick flanks of the Parc du Bastion-de-la-Reine; urban fishers hover above holes punched into the river ice; sled-pulling dogs thread their way through the old city's narrow lanes; skaters twirl on outdoor rinks and sculptors fabricate fantasies from hunks of blue ice. Who wants to stay indoors when all that's cool is happening outside?

So enticing is the cold, guests have booked out the famous Hôtel de Glace, a fantastical structure built anew each year from ice and snow. Though the inn is full, I take a tour around this frigid artwork with its fantastically themed rooms. Leaning against the frosty bar counter, I sip a neon-coloured cocktail from a glass carved from ice. In the chapel, I linger beneath vaulted ice ceilings on a fur-lined, ice-block pew; though polar clothing is mandatory in this frozen sanctuary, it's the site of many a warm-hearted wedding.

Such cold induces a ravenous appetite: after a day spent filling my lungs with winter's curative air, I'm enticed by the glow of restaurant windows from within the city's historic facades. Shutting out the snowstorm behind me, I enter Chez Boulay-bistro boreal, where deathly cold is supplanted by warm hearth. Here, celebrated chefs Jean-Luc Boulay and Arnaud Marchand apply French techniques to produce sourced from boreal forests – wild fruits and leaves and flowers, mushrooms, lichens. I replenish my energy with scallops from Gaspésie near the Gulf of St Lawrence, served with buckwheat and a jus made from balsam fir. Quebec's winter has seeped into my veins, and now its coniferous flavours, too.

The flurries have subsided by the time I emerge from the bistro, and so I make my way on foot through the still-bustling, light-struck streets to Bulles Whisky & Cie, a celebration of spirits within this carnival of snow. The DJ is spinning her turntable and mixologists are whirling their shakers as guests fling off their coats and seek succour in bubbles and whisky. But this this is more than just a binge-fest: participants are lured in from the cold by masterclasses with distillers and vintners and bars featuring spritzes and tonics as icy as the streets outside.

There don't appear to be any sore heads next day on the banks of the St Lawrence River, where spectators are lined up for the carnival's thrilling ice canoe race. Used as a form of transport across the frozen river during French colonial times, ice canoeing is now a competitive sport. From the comfort of the docked Quebec-Levis ferry, I watch as ant-sized athletes alternatively paddle through slush and thrust their craft over walls of shattered ice. It's an act of insubordination, a daring gallivant across an icy landscape that might open its maw at any moment and suck the canoeists in.

Long after the race has ended I commit an act of bravery myself: leaving my robe in a dressing room at Strom Spa Nordique, I head out into the stinging air dressed for a swim. But the chill is short-lived: goosebumps are vanquished as I sink into a steaming infinity pool perched high above the St Lawrence River; geothermally-warmed water enfolds me like a blanket.