Back in 1942, a bunch of Norwegians arrived in Scotland's Cairngorm mountain range and set about trying to blow up bits of it. They blew up rocks and they blew up roads. They even blew up some of the local fish by chucking grenades into Loch Morlich, the pretty stretch of water that lies at the heart of Glenmore Forest.
This sort of behaviour is not generally encouraged any more, particularly in the Cairngorm National Park. However, those particular Norwegians had an excuse: they were commandos training for an attack on a heavy-water factory in Nazi-occupied Norway. Their mission – sensationalised in the 1965 film The Heroes of Telemark, starring Kirk Douglas – was eventually successful, and their explosive story still forms part of landscape here in the Cairngorms. Literally so, as a man called Andy Bateman was keen to point out to me.
"See that stone up there?" he said, gesturing to a boulder poised 10 metres or so above the road leading up to the Cairngorm ski centre. I glanced upwards. It looked unremarkable. Roundish. Big. Boulder-shaped. "The back of it is smashed into bits. The Norwegians tried to blow it up. They didn't get very far." Perhaps that's not so very surprising. The Cairngorms – vast lumps of pink granite covered with heather and hikers – have been around for more than 40 million years. It takes more than a few sticks of dynamite to make a lasting impression.
I am not, by the way, Norwegian. I don't have the Scandinavian habit of doing national service. My cross-country skiing skills are as yet untested. Crucially, my knowledge of winter survival techniques is, or at least was until last month, confined to wearing gloves and a woolly hat during cold snaps. But that was before I met Andy, before I spent a night in the Cairngorms with him, before I dug my first snow hole.
First, some context: the Cairngorms are big. Not Alpine big, but certainly big in British terms. Sure, there's Ben Nevis over in the Grampians, but the Cairngorm range contains the second, third, fourth, fifth and sixth-highest mountains in Britain. These range from Cairn Gorm itself (4,084ft), which overlooks the now tranquil Loch Morlich, to the 4,295ft-high Ben MacDui, which rises just to the south. And if the Cairngorms are big, then the Cairngorms National Park has just got even bigger. Created in 2003, this vast chunk of north-east Scotland was already the largest national park in the UK before it was expanded southwards last year to include a patch of highland Perth and Kinross.
The point of all this is that you can get lost pretty easily in the Cairngorms, particularly in winter, and particularly if – like me – you have absolutely no idea what you're doing. And that's where Andy Bateman comes in. Andy runs a company called Mountain Innovations from Fraoch Lodge, a B&B/hostel in Boat of Garten, a village that took its name from a nearby ferry over the river Spey. He doesn't blow anything up, but he does run camping and hiking trips among the mountains during the summer, as well as navigation courses. And in the winter he takes people – even people like me – snow-holing.
Building a snow hole is the sort of thing those Norwegian commandos might have done in order to survive in freezing, hostile terrain. But Andy's technique was, he told me, very different from that used in Scandinavia, where temperatures plummet far lower than in the Cairngorms. "Scottish snow holes for Scottish conditions" is his mantra. "It's down to the time spent digging. Too little time means a snow hole that's too shallow, too small and too poorly ventilated."
I still didn't really know what he was talking about. What did a snow hole actually look like? Did it go down into the ground, or did you build it like an igloo? How cold would it get inside? And how was he going to fit five of us inside one?
Never mind, he was a qualified winter mountain leader, so presumably knew what he was doing – and at least I'd come prepared. Andy's pre-arrival instructions were clear: you need a decent amount of kit and reasonable fitness to hike these mountains in winter. A session in my local branch of Cotswold Outdoor had mustered a sleeping bag that would keep me warm at temperatures of -10C, a smart green waterproof jacket and a thick bedroll. I'd also been briefed on the importance of wearing base layers, fleeces and thermal socks – and had obtained a pair of gaiters. These were apparently very important, both to keep my legs dry and to protect my shins from being stabbed by crampons.
As I'd never worn gaiters before, or the special B2 rigid mountain walking boots that you need for crampon use, I was glad that part of Andy's three-day snow-holing course involved a session of winter mountain skills. But I was also slightly concerned. The other members of our party had form: Arlene, a legal secretary, had spent most of 2010 bagging Munros (Scottish mountains over 3,000ft), ticking off 70 of them in the process. Andrew, meanwhile, was a paramedic who'd spent a chunk of last year hiking up pointy stuff in the Himalayas. By way of contrast, I preferred my walks short, flat and with a pub at the end of them. I'd never even held an ice axe before.
It turns out that ice axes are important for winter hikers. You hold them in your uphill hand at the point where the shaft meets the head of the axe, with the spike facing backwards. This means you can jam it into the ground if you lose your footing and need to "self-arrest". Andy took us on a stiff walk past the skiers skidding down the icy slopes of Cairn Gorm – "If you can ski in Scotland, you can ski anywhere" – for some practice. As we crossed the snow-line and strapped on our crampons, a large white ptarmigan watched us, its croaking cry warning us to come no nearer.
We self-arrested for a bit, sliding down the mountain on our fronts and backs, rightside up and upside down. The key thing is to twist round as quickly as possible and use the weight of your body to force the ice axe in to the snow. If it wasn't a matter of life and death, it would be quite an amusing spectator sport.
The day was crisp and beautiful. From the top of Cairn Gorm we had a pixel-perfect view that stretched out over a plateau hemmed by peaks painted white with snow. And getting up top had been far from arduous: a brisk hike, albeit with some thigh-burning moments on the steeper sections. As dusk fell, we passed an ice-bound weather station, then watched the passage of one of the most beautiful sunsets I've ever seen: burning golds and oranges, with the wind whipping the snow on the tops of the mountains like steam.
Back at Fraoch Lodge that evening, the cosy front room was crammed with walkers and skiers, all describing their day on the mountains. I tried to join in, but gave up when the conversation turned to "v diff" climbing routes. Instead, I got stuck into the excellent chocolate cake made by Andy's partner Rebecca Field, which wasn't v diff at all.
Andy then gave us a briefing about what to expect on our trip, including a disconcerting piece of news. Mountain Innovations participates in the Cairngorm Poo Project, he said, which is designed to stop human waste being left on the mountains. Should we feel the urge, we'd be required to use a corn-starch bag and carry the results back down the mountain with us in a special canister for safe disposal. Reluctantly, I declined the offer of more cake. The next day would clearly be a test for some very important muscle groups.
Sandwiches packed, we were joined in the morning by the fifth member of our snow-holing expedition. Any hopes I had that he or she would prove to be as incompetent as myself were swiftly dispelled. Neil had trained for six years in the armed forces before starting his own back-country survival course in Aviemore. It turned out he could already self-arrest.
We spent a couple of hours winding round the western flank of Cairn Gorm before climbing the ridge above Coire an Lochain, a deep scoop in the mountainside. It all seemed quite manageable, just like the day before. But as we started to rise further, suddenly everything went white. Not white with grey bits, or white with lumps of scenery here or there. This was white without respite: a relentless, blank, white-on-white sort of white.
There's something exhilarating, and slightly terrifying, about being on a mountain yet not being able to see anything. The crisp views of the day before had now been replaced by a dense sheet of blanketing cloud. But Andy was reassuringly unperturbed. Working with Neil he set about the process of navigating without landmarks, using compass bearings and a timings chart that listed how far we were likely to travel in a given period, or over a set number of paces, with clever adjustments for ascents and descents. Occasionally he would stop, check that all was well with us, then march for 20 metres – north, south, east, west – to confirm the contours of the land. Then we'd be off again, braced against the wind, straining against our heavy rucksacks.
The change in weather conditions also marked a change in how I approached the trek. As the wind increased and the conditions worsened, I became very aware that we were tiny specks on a very big map; that as far as I knew we didn't have a tent with us; and that without Andy I would struggle to find my way back down the mountain, or even to survive.
At about 3pm, we stopped in front of a huge bank of snow. According to the map we were in a gully close to Garbh Uisge Beag – "rough little water" in Gaelic – but the monochrome landscape betrayed very little of note. Andy climbed the bank to test its stability, then gauged the depth of V Csnow with a long pole. Then he carved three metre-wide doorways into the snow, about halfway up the bank, and about a metre and a half apart. Shovels out: it was time to start digging.
We dug, and we dug, and we dug. We used saws to carve away huge blocks. We got sweaty, tired and wet. "We're not digging a snow hovel!" shouted Andy when there were signs of slacking. "We're building a snow hole!"
Night had fallen by the time we'd got a couple of metres in, so we used head-torches to light our way. Gradually an internal structure was formed; the areas behind the doorways were connected, then deepened. Four hours after we'd begun to dig, we had a long gallery in which to shelter. Then Andy carved a vaulted ceiling: we could now stand up. Snow hole? This was a snow home! We sealed up two of the exits with blocks of snow, unrolled our sleeping bags, and Andy started cooking dinner on a tiny camping stove, using melted snow for water.
The inside of a Cairngorm snow hole is a spectacular, if odd, place to spend the night. Andy had carved little cubby-holes for candles that bathed the inside in a warm yellow light; a band of ice ran through the walls in a glittering stripe.
As I fell asleep I tried not to think about the tonnes of snow heaped above our heads, or the drip of melting water from the ceiling. The wind had dropped, and outside ice crystals sparkled in the air, lit by starlight. I have never been anywhere so quiet.
There are almost certainly two sorts of snow-holing trip. One where you wake up to an ice-clear morning and a stunning view of the Cairngorms, and the other when the wind has increased to 55mph gusts, the visibility has dropped off further, your gloves are soaking and you've run out of chocolate. Guess which type mine was. Nevertheless, the other members of my group were keen to hike to the top of Ben MacDui (the second-highest mountain in Britain, remember). And for sensible, survival-based reasons, I decided to join them.
I can remember only snapshots of this journey: my hands gradually going numb, despite fresh gloves; icicles growing in Neil's beard; the metal of my ice-axe going sticky with cold; particles of snow collecting along the leading edge of every item of clothing or gear; the prints of crampons in the snow, like horribly extended animal claws. Andy would occasionally pause to point out various different forms of frozen water: rime ice, hoar frost, frost heave, windslab snow. Having navigated in these mountains for 12 years, he still expressed an infectious enthusiasm for this winter world, wind-chill and deafening wind notwithstanding.
Eventually we reached the cairn at the top of Ben MacDui, posed briefly for commemorative – if less than scenic – photos, and then began our long descent to the boulder-strewn greenery below. Despite my continuing status as a hiking novice, it had been an extraordinary journey. A snow-bound night in the Cairngorms tests your stamina and leaves you disorientated and dazzled in almost equal parts. But it also drives home the timeless and imposing nature of these mountains – and how fragile we are in comparison to them. You might not see much while you're up there, but for a proper sense of perspective, this is the place to be.
Travel essentials: Cairngorms
* Mountain Innovations (01479 831 331; scotmountain.co.uk) Fraoch Lodge, Deshar Road, Boat of Garten PH24 3BN. Snow-holing trips in 2011 are scheduled for 21-25 February, 5-9 March and 26-30 March, priced £389 per person based on two sharing, including three nights full-board accommodation at the lodge, one night in a snow-hole, snow-holing and cooking equipment, and transfers.
* The nearest train station is Aviemore, which is served by ScotRail (08457 55 00 33; scotrail.co.uk), with day trains and the Caledonian Sleeper service from London Euston. East Coast (08457 225 333; eastcoast.co.uk) has a daily train from King's Cross.
* The nearest airport is Inverness, which is served by Flybe (0871 700 2000; flybe.com) from Belfast, Benbecula, Birmingham, Edinburgh, Gatwick, Kirkwall, Manchester and Stornoway, and by easyJet (0905 821 0905; easyJet.com) from Bristol, Gatwick and Luton.
* Cotswold Outdoor (0844 557 7755; cotswoldoutdoor.com) has a range of specialist equipment for winter hiking trips including clothing, sleeping bags and footwear.
* Crampons, B2 walking boots and ice axes can also be hired from Mountain Spirit (01479 811788; mountainspirit.co.uk) at 62 Grampian Road, Aviemore.