The evening flight from Oslo left the darkness of mainland Norway behind as the plane flew due north, past the Arctic Circle and into the full glare of the midnight sun.

As we approached Spitsbergen – the largest island in Svalbard – I looked down on a vista of black volcanic mountains and blindingly-white glaciers. From this far north the plane would have reached the North Pole in just over an hour but instead the pilots change course for the final approach to Longyearbyen, Spitsbergen’s main settlement.

Although I am used to Scotland’s long summer nights nothing had quite prepared me for the 24-hours of sunlight that Svalbard, at 78 degrees north, enjoys for at least four months of the year. We land shortly after midnight but it might as well be midday. Once I have reclaimed my bags from the luggage carousel the first thing I reach for are my sunglasses.

I am here to take part in a ten-day glacier-walking expedition and have arrived ahead of the rest of the group to have a look around Longyearbyen and its surroundings before the trek gets underway.

The town has the feel of a Klondike gold-rush camp but is also surprisingly cosmopolitan and thriving. Environmental scientists from around the world rub shoulders in the town’s pubs and cafés with tourists, students and adventure guides.

There is a school, a couple of museums, outdoor equipment stores, tourist shops, restaurants, a supermarket, a post-office, a hospital, a sports centre, a cinema and a university.

There are even a couple of four-star hotels for those who want a touch of luxury before their excursion into the Arctic wilderness. At the town’s only bank a sign asks customers to leave their rifles outside the building.

In the middle of the town, reindeer can be seen grazing around the brightly-coloured wooden buildings and Arctic foxes scurry under the network of insulated pipes that connect all buildings to a district-heating scheme fired by the town’s coal mine. The penetrating permafrost means that the town’s plumbing has to be above the ground.

The rest of the party arrives the following day and we board a boat for the four-hour trip to Petuniabukta, in the heart of Spitsbergen, where we are to set up a base camp.

On the way we see a good number of Svalbard’s sea birds, which are surprisingly similar to Scotland’s: guillemots, gulls, puffins, fulmars, kittiwakes, Arctic skuas, terns and eider ducks.

From the boat we are shuttled ashore by dinghy along with heavy boxes of supplies. Once the tents are up, our guides Kristin and Henrik set up a trip-wire around the camp and brief us on what to do if a hungry polar bear shows up at night.

Theoretically, any breach of the trip-wire will set off warning flares which should wake us and scare away the bear. If that doesn’t work, the guides are equipped with large-bore rifles and have been trained to shoot to kill if necessary.

There are believed to be over 3000 bears in Svalbard (slightly higher than the human population of 2500) but in the summer months they tend to follow their natural food source – seals – close to the drift ice and pack ice along Spitsbergen’s northern and eastern coasts.

We didn’t see any, but on the last night of the trip an adult bear was shot by a guide some twenty miles from our camp after it got dangerously close to a party of day-trippers on a cruise boat. A photo of its bloody 700-kilo carcass makes it to the front page of the local paper Svalbardposten and, as the polar bear is a protected species, a police inquiry is launched.

For the next few days we make a number of progressively harder day walks from our base camp in preparation for a four-day expedition across the Mittag-Lefflerbreen: one of Spitsbergen’s largest glaciers.

Each day we walk for around twelve hours and take in the occasional Munro-sized peak including Tarantallen, a dramatic double-arched pinnacle that resembles a spider which juts out from a nearby mountain ridge. The terrain is tough-going and almost every day involves strenuous glacier and river crossings.

Around our camp the low-lying tundra is surprisingly fertile and colourful. A friendly reindeer spends much of his time nearby chomping the vivid mosses and the stones are covered in bright green and orange lichens and purple saxifrage.

One of the easier walks is to the abandoned Russian coal-mining settlement of Pyramiden. Named after the pyramid-shaped mountain above it which is scarred with rusting mining equipment, the town was home to over a thousand miners until 1998 when the mine was suddenly closed down and the entire population evacuated to Russia.

The desolate ghost town is similar to Spitsbergen’s other Russian mining settlement at Barentsburg, which – for the moment anyway – remains open. But the rumour among the Norwegian community is that Barentsburg is no longer economic to mine and is kept open by the Russian authorities for purely territorial reasons.

After the First World War the Svalbard Treaty gave control over the archipelago to Norway, and the Soviet Union was given mineral rights which would be hard to re-establish if Russia pulled out completely.

The loss of jobs at Pyramiden has been compensated for by the recent opening of a massive new Norwegian-run mine at Sveagruva. Although the melting of the polar icecap has become the most potent symbol of the dangers of global warming it is a strange paradox that the main source of employment in Spitsbergen remains the mining of fossil fuels.

The harshness of the Arctic winters has taken its toll on the state of the buildings in Pyramiden over the last decade and glaucous gulls use the windowsills of the neglected Soviet-style flats as nesting sites.

The town had its own kindergarten, primary school, cat’s graveyard and greenhouses as well as the world’s most northerly swimming pool, Palace of Culture and statue of Lenin. But the whole settlement is now in danger of being swept away by flood water as the gravel walls which guided rivers around the settlement have burst their banks and there is no-one left to maintain them.

The day before our expedition to the Mittag-Lefflerbreen is designated a rest and – as we have not had a shower for five days – sauna day.

We scour the shores of the bay for an hour or so and eventually find enough wood to start a campfire. Over several hours a large boulder is then heated to boiling point before being carefully transferred into one of the tents, now brought into service as an improvised sauna.

The water spits and hisses as it is ladled onto the stone and sulphourous-smelling steam soon fills the tent. When it gets too hot to remain we plunge our poached tingling bodies into the icy cold waters of the Billefjorden. The contrast in temperature from the steaming vapour of the sauna to the near-freezing seawater is a shock to the system but we joyfully huddle back to the sauna and repeat the process a couple more times.

Normally associated with spas in luxury hotels, to have a sauna in the middle of the Arctic tundra was a truly elemental and invigorating experience.

The next day we set off with heavy overnight packs for the Mittag-Leffler glacier. It should have been the highlight of the trip but low cloud descends almost as soon as we set foot on the Ragnarbreen, the first of the glaciers that we cross that day.

To make matters worse one of the group with a sore foot is approaching the end of her tether.

Soon after reaching the Mittag-Lefflerbreen I feel a sharp yank on the rope as the woman ahead of me falls through a snow bridge into a deep crevasse. I unsuccessfully attempt to plunge my ice axe into the hard blue ice of the glacier but the rope and the combined weight of 13 people has taken the weight.

A quarter of an hour later, after setting up an elaborate pulley mechanism, Kristin and Henrik manage to pull a bruised and shivering Gillian out of the crevasse and we resume our slow plod across the glacier.

After twelve hours of walking in freezing fog we eventually clamber on to a nunatak (a rocky ridge not covered with snow) called Heclastakken in the middle of the glacier where we set up an advanced camp. The rocky outcrop is in the middle of a five-mile wide sea of ice surrounded by dark, brooding mountains.

When the mist clears we get tantalising glimpses of the surrounding mountains whose strangely stratified and pointed peaks give Spitsbergen its name. In the distance is Newtontoppen. At 1717 metres it is the highest mountain in Svalbard.

The plan had been to spend the next couple of days bagging a few peaks but the following morning Marisa’s foot shows no signs of recovery. Our guides use a satellite phone to summon a helicopter but the thickening fog makes a rescue mission impossible.

There’s nothing else for it and we decide to abandon the expedition. We pack our tents and re-trace our steps across the glacier back to base camp, which we reach shortly before midnight. Dinner is served in the early hours of the morning.

A couple of days later the boat from Longyearbyen arrives in the bay to pick us up for the journey back to civilisation. After ten days in the wilderness the simple pleasure of a hot shower has never seemed so beguiling. Once we have scrambled on board the Langøysund, the ship’s crew prepares a delicious barbecue with Norwegian pancakes and ice cream for desert.

On the way back to Longyearbyen our boat passes close to cliffs of nesting seabirds as well as the massive Nordenskiöld glacier which calves into the fjord on the opposite side of the bay from our camp. As the boat approaches the 100ft-high sheer ice wall of the glacier a muffled cracking noise rends the air and a sizeable chunk of ice from the glacier crashes into the sea.

The ship’s barman scoops up some of the thousand-year-old ice from the sea and mixes it with evening cocktails which are served on deck to celebrate the end of the tour. As the fulmars dart their way past the bows of our boat we savour our gin and tonics and toast the guides for bringing us to this magical place.

Getting there

Norwegian Air Shuttle flies from Edinburgh to Longyearbyen several times a week with a change of planes in Oslo. Return fares from £290.30. norwegian.no

Trekking

Svalbard Trekking organises various hikes in Spitsbergen from one-day guided walks to multi-day treks. The firm’s four-day hike from Longyearbyen to Barentsburg, with accommodation in tents, costs 6399 Norwegian kroners (£590) per person.

Useful website

Svalbard Tourism: visitsvalbard.com