My first assignment in Antarctica, for High Life magazine. What a trip.

Trust my boots? What does he mean, trust my boots? Just look at that slope! It’s slippery. The rocks down there, the furious sea. The mountains are watching. There are people behind me. Why should I trust my boots? I don’t trust my boots!

But the glaciologist just digs his right foot deeper into the snow, and reads my mind.

“Look,” he says, turning towards me, away from the drop. “There’s a million years of evolution gone into you. Everything works. Point your toes in the direction you want to go, then make the step. Trust your boots.”

I’m fine, of course: they are good boots. It’s steep, and snowy, and icy. There are rocks, and the rocks don’t care whether they tear my flesh or not. The air is colder than freezing, and the wind blows snow in sideways, embedding chill into my cheekbones. And this is serious wind, whooping in over the razor mountains from the inconceivable immensities of ocean just beyond. But I’ve barely stopped grinning all week. I’m in places I never imagined I’d ever be.

That’s the thing about travel in Antarctica. It strips you bare. You may be in a group, but you’re on your own. There’s no development of any kind – no people, no towns, no shops, no roads, no paths, no signposts, no useful handholds, no steps or railings to show you the way. There is nothing, and everything. It is pure, joyous, eternal wilderness.

But the flipside of that is, well, you’re on your own. With freedom comes responsibility. Nobody can save you, if you venture onto the sheet ice and slide all the way down the mountain into the furious sea. And if you care to look, my friend, you’ll see that the sheet ice begins half a metre from where your left boot is right now, so I’d advise you to step this way a little. (I’m not making it up: that is a direct quote from one of the guides on my trip.)

It’s up to you, to look and to think. Not to go to the very edge of the precipice, even though there’s no barrier. Not to walk on an apparently solid field of virgin snow if someone who knows better says don’t. Antarctica is a test of character: unlike anywhere else in the well-regulated world of adventure travel, it presents the foolhardy with the ultimate challenge. Push your boundaries, but remember that the nearest hospital is 700 miles away and there are no rescue helicopters on standby in case it all goes pear-shaped. Even if you like to go off beaten tracks, you will never have been as far off any beaten track as when you go to Antarctica.

Why visit? For the wildlife, yes. For the landscapes and the wilderness. To tick off the seventh continent. Even to follow in the footsteps of European explorers: Norwegian Roald Amundsen was first to the South Pole in December 1911, beating a British team under Robert Falcon Scott by 33 days – and this month marks exactly 100 years since the Endurance, led by another Briton, Ernest Shackleton, sailed south on what was to become one of the most celebrated of all polar adventures.

Unlike populated places, Antarctica hasn’t been allowed to throw off its dead heroes and their ambitions. Bearded ghosts jostle to shape your expectations. But try to resist: an open continent deserves an open mind.

It’s surprisingly easy to arrive. Throughout the austral summer – roughly November to March – cruise ships of all shapes, sizes and comfort ratings set out for Antarctica. Almost all start from Ushuaia, a ramshackle port town at the southern tip of Argentina, bound for the Antarctic Peninsula, a finger-like prominence of mountains that forms a southern extension of the Andes. According to the International Association of Antarctica Tour Operators (IAATO), some 27,000 tourists set foot on Antarctica last year. A few thousand more overflew in chartered sightseeing flights or travelled on large cruise ships that, because of their size, are forbidden to land passengers ashore.

It’s also not as expensive as you might think. If you’re prepared to kill time in Ushuaia keeping your ear to the ground, you could get lucky and find a last-minute booking on a frill-free ship for as little as £2,500. Then again, joining a whistle-stop itinerary that flies you to the South Pole and out again could cost £30,000.

But flying undercuts one of the best aspects of an Antarctic journey: the slowness of the approach. At Ushuaia I board Silversea’s ice-strengthened cruise ship Silver Explorer, which operates 10-day luxury voyages around the Peninsula from about £6,000. Two days are taken up sailing the Drake Passage, the notoriously choppy stretch of ocean south of Cape Horn. We are lucky to experience a “Drake Lake” – but we could have undergone the “Drake Shake” amid storm-swells topping 15m. Yet, even with a seasickness patch stuck behind your ear, the Drake is all about delayed gratification. Taking time to reach an unknown destination – and taking time to return to the everyday world afterwards – is delicious.

Thankfully, Antarctic tourism is strictly regulated. On Day 1 we report to the ship’s ‘mud room’ for our coat pockets and beanie hats to be vacuumed clean of seeds, spores or bugs that might threaten the Antarctic ecosystem. Before and after going ashore, we squirt our boots with Virkon, an agricultural disinfectant that cuts transmission of disease through unwitting transfer of penguin guano. Silver Explorer, like all ships voyaging in Antarctic waters, runs on special light diesel that, in case of spills, will float and evaporate harmlessly. Pumping bilge water is prohibited, and grey water from showers and toilets is biochemically treated before being pumped in open sea. Food waste, plastics and metal are collected for unloading in Ushuaia.

Yet Antarctica is not a country: it has no government, no state institutions and no indigenous population. Instead, the entire continent is set aside as a scientific preserve. The Antarctic Treaty, which came into force in 1961, enshrines an ideal of scientific freedom and the exchange of knowledge. Military activity is banned, as is prospecting for minerals. Fifty states have now ratified the treaty and its associated agreements.

Maps of Antarctica show borders radiating out from the South Pole, slicing up the continent like an apple pie. Norway, Australia, France and New Zealand lay claim to large portions, while Chile, Argentina and the UK have overlapping claims centred on the Peninsula. But Antarctica’s borders are a political fantasy (at least, while the treaty holds). Land claims are not recognised by the international community, and anyway, a pot-pourri of countries maintain scientific bases all across the continent – the seven nations listed above, as well as the US, Russia, China, Brazil and many more, from Ukraine to Uruguay. In practice Antarctica is everyone’s.

Except when you’re there, it feels like no one’s. As well as the coldest, windiest, darkest (in winter), lightest (in summer), highest (above the ice) and lowest (below the ice) of the world’s continents, this is also the driest. Every other desert, from Arizona to Arabia, is a human place: people live in or around it, people find sustenance and life in it, people shape it with their ingenuity and their imagination. But nobody shapes Antarctica’s white desert. It is inhuman. Impenetrable. Quite literally incredible.

We land first at a frigid beach of mud and guano in the South Shetland islands, where Silver Explorer drops anchor in a snow-fringed bay. Expedition guides buzz us ashore in rigid inflatables known as Zodiacs. A desultory ocean laps under gaunt black crags that ring with the exultant cries of nesting gentoo penguins, sleeker than imagination. I sit for a while as the penguins wait for their partners to bring them fish, wait for their chicks to grow, wait to learn what unwelcome dramas the next moment might unleash. More penguins patter past, eyeing me but apparently uncaring, heedlessly colouring a monochrome world with their yellow feet, their pebbly nests green with moss, and their guano turned reddish by a diet of krill (a kind of ocean shrimp).

We voyage from Desolation Island, an active volcano in South Shetland, to Brown Bluff, an englacial volcano on the Antarctic mainland. Every step, every second, I try to fix the beauty in my mind. We down home-distilled vodka with a half-dozen Ukrainian scientists at ice-bound Vernadsky Base, their first visitors in a month. At Neko Harbour, an empty bay on the Antarctic Peninsula, I am lucky enough to witness a glacier calving before my eyes, with a sound I could never describe and will never forget. We see three species of penguins and four of seals, albatrosses, skuas and petrels galore, and – most memorably – humpback whales and a family pod of orcas, mothers nudging calves to ride our bow-wave.

The sunsets, which linger into the midnight hours, drench us in pinks and lilacs, turquoises and lavenders. Colours are utterly unexpected, in a white place. Late one night on the freezing deck, while the ship is quiet, I watch day-bright clouds fade eerily to shades of strawberry and copper-green. Creamy glaciers on each side turn unearthly peach and vanilla, framing distant peaks. The mountains are bright blue.

In my years BA (“Before Antarctica”) I always thought talk of blue ice was poetic licence, perhaps hinting at a wash of reflected light. Now I know better. Glacial ice can appear cobalt blue. Compression during formation eliminates air bubbles, and dense ice absorbs more blue light. It isn’t blue – but it looks it.

At the sight of the blue mountains Gennady, a taciturn Muscovite on his second visit to Antarctica, runs a hand over his chin beside me. “That colour doesn’t exist in nature,” he murmurs, as if to himself.

We become friends. It feels global aboard Silver Explorer: there are 15 nationalities among the ship’s 114 passengers, and 22 nationalities among the 120 crew. Unlike ordinary cruise ships, there is only one bar, one restaurant, one lounge. With the informality of open seating, and Silversea’s all-inclusive pricing policy that covers all food, drink and tips, the atmosphere is more like a members’ club than a commercial cruise. People swap tables to chat, often between courses.

An extended Taiwanese-American family is on the trip of a lifetime. Herbert, aged 35, has quit his high-powered job in Hong Kong to travel the world. Dennis, aged 70, is from Perth in Australia, and has never seen snow before; we stand together on deck as flakes settle momentously. Monica from New Jersey wasn’t meant to come at all, but her friend’s husband couldn’t make it, so she was a last-minute shoo-in. Heinz and Sabin from Zurich are on a 40th-anniversary adventure. Within a couple of days the maitre d’ and waiting staff are greeting us all by name.

Our guides – biologists, geologists, glaciologists, historians, climatologists – fill days at sea and free afternoons with a cycle of lecture presentations, from stories of Scott and Shackleton to analyses of seal behaviour and tips on seabird-spotting. Expedition leader Kara Weller, from Alaska – who describes herself as a “bad biologist” – is on her 112th visit to Antarctica.

“I grew up in the Arctic,” she says. “It was wild and open; I appreciate these vast, dramatic landscapes. But the reality of Antarctica exceeds everyone’s expectations. It’s grander than it appears in photos.”

And we live for those few hours each day when we can leave the world of fine dining and butler service for that other reality. The rewards for heading out are so stupendous that the logistical prepping required for shore landings becomes part of the pleasure of anticipation.

First you strip. Then, the base layer – a body-fitting long-sleeved thermal top and leggings of merino wool, plus merino under-socks. Then a mid-layer: T-shirt and fleece, breathable trousers, mid-weight socks. Then an outer layer: lined and waterproof ski pants, thick-soled rubber boots (loaned by Silversea to every Antarctic passenger), merino neck garter, two hats and the fleece-lined parka that Silversea offers as a gift. Then lip balm, sunglasses, sunblock on nose and cheeks, silk inner gloves and – finally – fleecy high-performance ski mitts.

Getting dressed was never so much fun. I would be comfortable in -30C – though we rarely experience temperatures as low as -5C (though the windchill sometimes makes it feel much sharper).

And we are visiting just about the fastest-warming place on the planet. As our biologist guide and climate specialist Claudia Holgate explains, average temperatures on the Antarctic Peninsula have risen almost 3C over the last fifty years. Warmer air is able to hold more moisture, so the peninsula is now seeing more snowfall, and even rain. Even ignoring global issues of glacier melt, one local effect of climate change, she points out, is that land is being flooded more often, leading to penguins’ eggs freezing or drowning in the nest. Gentoos will re-lay, but other species, notably chinstraps and Adélies, will not. They are starting to move further and further south, away from the peninsula, in search of colder, drier conditions. But this is already the coldest place on earth – and you can only go so far south before you start going north again. Like polar bears in the Arctic, the penguins’ habitat is shrinking, perhaps irrevocably.

Human action may be starting to shape Antarctica, with implications for us all. That’s an easy sentence to write; even easier to read. But it’s hard to care about – unless you come and see Antarctica for yourself. Visiting plants a seed in the mind. By setting foot on the ice, you give yourself the chance to care about it.

One morning we wake to blue skies. Silver Explorer noses a path through the Antarctic Sound, untidily littered with half-melted icebergs sidling north out of the Weddell Sea, and we pause in sun-filled Kinnes Cove. At sea level, beside the greenish subsurface immensities of icebergs, beneath whipped-cream glaciers and sunny views so big they stretch comprehension, human perspectives shift.

“You see that berg?” says Alex, our Zodiac guide. He points to a tabular white mass just across the bay, looming high. “Looks close, right? It would take us more than an hour to get there, at full speed. It’s about 30 miles away.”

Each person bobs quietly, together but alone, bathed in blue under the glittering embrace of the sun. Small becomes big. Far seems near. Light is everywhere. You could only wish the end of the world might be like this.