Almost silently, my leg slides shin-deep into a deceptively soft drift of fresh, pillowy snow. It's -16°C outside but the wind whipping around the side of the summit is making the cold bite a few degrees lower than that. The damp, searching chill burrows through the weave of my gloves, the breeze ripples and snaps at my trousers and my hair has frozen into several long, crisp lengths of string. I stab the handle of my ice axe deep into the snow to steady myself before taking another step. The inch-wide hole I've made glows back at me in a bright shade of White Walker blue.

I'm walking on the mid-cornice of Snaefellsjökull, a 700,000-year-old glacier-capped volcano found at the western tip of Iceland's Snaefellsnes peninsula. To make it here, me, my driver Borgthor and a team of mountaineers from local tour operator Summit Adventure Guides have tracked through a whiteout in the back of a Snowcat, watching the altitude tick slowly towards 1,400m as we stare at a fuzzy, all-white video feed on one screen, and a satellite map full of waypoints and crevasse warnings on another.

These days, it's volcanoes like this one that make Iceland a popular place to visit, giving people the feeling of being at some ancient, untouched end of the Earth, when they're actually just a couple of hours in a plane from the rest of Europe. But it was a volcano that got us there in the first place, too. Back in 2010, the gigantic ash cloud created by the eruption of Eyjafjallajökull in the south of Iceland grounded planes across parts of Europe for two weeks, forcing an island that sits on its own at the farthest end of Europe to rocket to the very forefront of global awareness. Since then – with the help of some pretty absurd natural scenery – tourism has catapulted from side-gig to economy driver, with the number of annual tourists now outweighing the country's year-round inhabitants 2.3m to 338,000.

But with such a vast increase in visitors, you need to strike out somewhere different to discover the true away-from-it-all feel; for every Blue Lagoon, iconic waterfall and busy black sand beach, there are four or five sights that are a lot less crowded and equally as epic, if a little harder to reach in the confines of a long weekend or stopover. And that's why I find myself here: atop a sleeping giant at the narrow end of Iceland's Western Region, padding slowly through a whiteout while trying to guess what the landscape a kilometre below me looks like through clouds pregnant with snow.

Snaefellsnes, west Iceland: Snaefellsjokull glacier

i stab my ice axe deep into the snow and the inch-wide hole i’ve made glows back at me in bright, white walker blue

"It's a lottery," says my guide Thor Magnusson, open-jacketed and gloveless in spite of the chilling wind. "If you make it here at all, you're lucky." And he's not wrong – when you're surrounded by a web of snow-covered crevasses and thin shelves of ice dropping off 100ft or more, you wouldn't want to travel in much worse conditions than this. But as a long-time search and rescue volunteer on this very glacier, Magnusson knows how to read the weather and the land, leading treks and expeditions all year round, and even helping a handful of adventurers ski down from the very top of Snaefellsjökull if the conditions are right during spring. It's with his knowing shrug and a few words, then, that the sun bursts like an opening eye through the clouds, revealing the snow-covered landscape down to the Atlantic out west, and forming a vast white rainbow through the fast-disappearing fog.

"They say if you don't like the weather in Iceland, you just have to wait five minutes," he says, smiling, and starts handing out flasks of coffee and hot chocolate.

Back at the base on the north-west coast, the sun burns bright through a bluebird sky, my wind-bitten skin rushing hot and cold as I gaze back up at the knobbly, candle-stump-shaped summit a few miles in the distance. Jumping back in the car with Borgthor I track coastal roads around the end of the peninsula, watching mountains morph in shape and size as we drive round them – some jagged, some soft, some conical, some perfectly symmetrical. We travel along roads positioned away from cliffs to avoid falling boulders, we pass screeching colonies of fulmars and cormorants, we go through villages where football pitches sit at the feet of mountains, and when we reach a carpark perched between broad tussocky meadows and the roaring Atlantic, we come to a stop.

I slide the car door shut, pull on my hat and stroll alongside Borgthor towards a nearby trail, the car's snow spikes glinting in the mid-afternoon light.

"The locals often say that Snaefellsnes is like all of Iceland in one place", he says, gesturing to the mountains and meadows, and guiding me down to the black pebble beach of Djúpalónssandur below. Once the site of a fishing settlement, it still holds relics of its maritime past: four time-weathered rocks of different sizes that were once used to determine the strength of would-be fisherman before they were sent out to sea, and the debris of a wrecked trawler from Grimsby that washed up here in 1948. These days, though, it's better known for the black, pearl-like shingle that makes up the arch-shaped bay, and the hulking stack of dark volcanic basalt that flanks it. It's one of the most iconic beaches in the Snaefellsjökull National Park – a 170km2 expanse of open country at the westernmost end of the peninsula that stretches from the sea to the summit of Snaefellsjökull.

Outside the park itself, the scenery scarcely lets up, either: along the peninsula's southern side, the ancient fishing villages of Hellnar and Búdir cut impressive figures between the waves and the mountains, the former complete with a mighty arch of lava-formed rock, and the latter with a defiantly tiny church built from black wood set alongside an isolated guesthouse called Hotel Búdir, where we rest for the night.

Snaefellsnes, Iceland: Langjokull glacier
Snaefellsnes, Iceland: Kirkjufell mountain

Striking, symmetrical and completely otherworldly, kirkjufell is the most photographed mountain in Iceland

Not long after sunrise the next morning, we leave behind the calm waters of Búdir and take the road through the mountains just as it starts to snow. Borgthor winds along the empty road for 20 minutes, passing a single emergency mountain hut and one other traveller before plunging down towards the sea and getting coughed out on the north side of the peninsula. Head west from here and you're soon back in Snaefellsjökull National Park, head east – where we're going – and you're swallowed by flatiron-shaped mountains as the road weaves between sea fjords and slender necks of lowland.

For half an hour, we stop at the arrowhead-shaped mountain of Kirkjufell, which is famous for its repeat appearances on Game of Thrones and your Instagram feed. Striking, symmetrical and completely otherworldly, it's the most photographed mountain in Iceland, and it shows: the pathway up to the viewpoint is slippery with footfall-polished ice, and several photographers stand in a row lining up the perfect shot of the mountain with its famous accompanying waterfall in the foreground.
I bury my pride and join them.

Heading further east – past the sleepy fishing town of Stykkishólmur and off the peninsula – you quickly hit the ring road. If you follow it, this circular artery takes you all the way around Iceland, to the Westfjords and Akureyri in the north, past the fjords of the lesser-visited east coast and back to Reykjavik and the much-loved Golden Circle via the river deltas of the south. But venture within that, and you find all kinds of landscape: mountain ranges with outrageous views, volcanic craters you can hike through, a glacier the size of London and the home counties, and highland plains inhabited by stocky, shaggy-haired Icelandic horses.

On my return journey south to Reykjavik, I only have time to stop in at Húsafell – a farmstead, adventure centre, hotel and hot spring baths that makes for one luxurious base camp for the surrounding mountains. Head in one direction and you've got a wide valley full of trails, snaking streams and hidden waterfalls, while the other leads you through low-slung birch forest, then across a highland tundra that gives way to the great whiteness of the Langjökull glacier.

Making up roughly 1% of Iceland's landmass, the Langjökull ice cap is 600m deep at its thickest point, and covers roughly 950sq km. In part for glacial research and in part for tourist education, Langjökull is home to Into the Glacier, the world's longest man-made ice tunnel, stretching a 550m-long heart-shaped loop under the surface of the ice.

The next day, we tackle the glacier in the back of a beast: eight 58-inch tyres carry us along the lava field at the foot of the ice cap, the cab of the truck lurching sideways on big, soft suspension as mountains capped with blue ice come and go faintly through the fog. Shortly after reaching the snow-covered summer base camp, we disappear into complete whiteness. Glaciers like this are so mighty that they swallow you into their own weather system the moment you cross the threshold between rock and ice, forcing you up a single perilous route on their complex, crevasse-cracked faces. For 45 minutes in the swirling white, there is nothing save for the 18 people in the back of the truck, the insistent thrum of the engine and the occasional bamboo road marker brushing past the fogged-up window.

Then with a jolt we're at the top, where we dip out of the whiteness into a small tunnel opening and wander down a cold, carpeted passageway towards a faint aquamarine glow. When the carpet runs out, we clip on crampons and start our gentle descent, going back further and further into the glacier's 8,000-year history with each step. The youngest ice here is roughly 25 years old; by the time we reach the tunnel's furthest reaches, we're walking on azure blue, oxygen-starved ice from the early 1700s.

we dip out of the whiteness and wander down a cold, carpeted passageway towards a faint aquamarine glow

But this won't be here forever. On the way around, we encounter moulins and crevasses through which the glacier is slowly falling away, each ferrying a little bit of meltwater to the base of the glacier where it makes streams, joins rivers and eventually finds its way out to the Atlantic to supply minerals to the ocean. Although this is perfectly natural glacial activity, it's happening at an alarming rate. In fact, just four miles to the south of Húsafell, the glacier at Ok retreated to such an insignificant size that it became Iceland's first glacier to be delisted back in 2014. According to different forecasts, the same could happen to Langjökull within the next 50 to 150 years. The tunnels – by then long-empty and closed to tourists – will seal themselves as they slide down the lava field and disappear completely.

Waking at Húsafell the next day, I slip into my thermals and slide out of the door into the biting frost. I descend the stairs by the steaming outdoor baths and make for a frozen waterfall in a small canyon across the river. I climb up one side of the gorge, breaking a sweat as the sun crowns the peaks pink. Onwards I go, hopping across tiny frozen streams running down the hillside, scrambling across the shiny ice on my hands and knees. Near the top, I take a seat on a solitary bench next to a metal box containing a guestbook wrapped in a sandwich bag. I sign it, then pause, looking over the valley and listening to meltwater running out at the base of the falls a hundred feet below.

Getting there

Icelandair flies from London Heathrow to Reykjavik from £127 return. icelandair.com; for more information on holidays to West Iceland, visit inspiredbyiceland.com or west.is

"It's a lottery," I think to myself, looking at all the things that have aligned for me to be here in this moment: the ice caps on this island that help keep our planet hospitable, the millenia-old lava that I'm standing on and – perhaps most insignificant of all – the thick volcanic ash of Eyjafjallajökull that made the world sit up and notice Iceland almost a decade ago. Thor was right: If you make it here at all, you're lucky.