It was the question on all of our minds, but I asked it: "How do you know when the ice isn't safe to skate on?" Niklas, our imperturbable guide, rubbed his chin, looked thoughtful for a moment, then offered up the distilled wisdom of a lifetime spent playing around on frozen water. "When it breaks," he said with a broad smile.
The comment wasn't exactly reassuring, but his easy confidence was. As long as it was just jokes being cracked, maybe we'd be alright after all.
Niklas, a maths teacher in breaks between pursuing his passion, wasn't being entirely facetious. Unencumbered by the inquest-fuelled paranoia that defines most Britons' relationship with natural ice, the Swedes adopt a common-sense approach: they exercise caution, they test as they go, and they use ears, as well as eyes, to evaluate. Sturdy ice makes a deep, sonorous noise underfoot; thin ice, something altogether more high-pitched.
Our mostly female group was firmly in the latter camp as we massed at the edge of a vast frozen bay that first day. Niklas tried his best to coax us forward but, like dithering penguins on an ice floe, no-one wanted to take the first step. Ten minutes later we sneered at our earlier caution as we glided across a surface with the solidity and finish of marble, our joy as unconfined as our surroundings. "Look at your faces," shouted Niklas to the euphorically gurning convoy, racing along behind.
Our expressions had been far less ecstatic the previous evening on being told that a five-hour drive would follow our respective flights into Sweden's Arlanda airport. That hadn't been the plan; but then, in the world of natural ice skating, no-one sets much store by plans.
With its innumerable waterways (it has nearly 100,000 lakes alone) and sustained sub-zero temperatures, Sweden has no shortage of ice. This is not always suited to skating, however. Too much overlying snow and you get a bumpy, uneven ride; a sudden thaw and great swathes become unusable.
Perfect conditions must be sought out, and don't last. Hence our impromptu drive from one side of the country to the other. Niklas had received a tip-off from a skating forum about Stigfjorden, a shallow, island-studded bay around 30 miles north of Gothenburg on the west coast.
It was past midnight when we arrived at the hastily booked hostel in the hamlet of Odsmal. Low winter demand means it is always possible to find a room in one of these cosy, wood-clad vandrarhems (literally "hiking homes"). They're often unmanned and the "leave it as you found it" principle is scrupulously observed.
The kit we were issued with the following morning included knee pads, elbow pads and backpacks fitted with detachable spikes for clawing a path out of an ice hole. The skates consisted of removable blades that fastened to the toes of our specialist boots like cross-country skis.
Free from the constraints of perpetual turning and toddler dodging, ice skating is a wonderfully leisurely affair, we discovered. Push off with one skate and you can coast 30ft with ease. Two or three quick chops at the surface and you accelerate like a top-class sprinter. Covering distances of 150 miles in a single day is not unknown.
This hyper-mobility is a great leveller; the quickest member of our multi-national group of nine beginners proved to be a Swiss sexagenarian, Beat, much loved for the glutinous treats he'd distribute during packed-lunch stops.
That first day we ate among the caramel-coloured boulders and lime-green lichen of one of Stigfjorden's tiny islands, frosted waterfalls flowing unmovingly down distant granite cliffs. A lone swan beating overhead was all that disturbed the icy serenity. We stayed out on the bay as long as ankles and chilly noses permitted, before retreating to the hostel for a feast of reindeer stew and lingonberry jam prepared by junior guides Christin and Erik.
The next morning found us 60 miles down the coast at Kungsbacka, chasing another tip-off. It proved as sound as the ice, and the "yachties" had also got wind of this 20-square-mile playground. Picture a streamlined Topper or Laser controlled from a supine position like a luge and moving with the velocity of a powerboat. We watched 30 of these come together for a race, the carving of steel runners on ice generating a sound like a jumbo jet landing.
In its more glacially paced way, the ice itself was equally enthralling. Skating in a westerly arc, we came across a Lilliputian mountain range, points of weakness forced upwards into perfectly conical, knee-high eruptions. Further on, where ice segued into open sea, the current had painted billowing clouds and spectral swirls on the underside of the transparent canvas.
The best was saved until last. Vattern, in the centre of the country, is one of Europe's biggest lakes, and one of its clearest. In ideal conditions, this clarity creates an ephemeral phenomenon known as "glass ice". For skaters, it doesn't get much better.
"It's like flying," Erik told me excitedly during our three-hour drive through a quintessential Swedish landscape of heaped snow and Falu red farmhouses. Parking up on a narrow wooded isthmus, we clipped on skates and wobbled inelegantly across giant slabs of ice forced together like crazy paving.
Abruptly, this ended. We paused. The rocky lake bottom stretched beneath us, 10ft below a surface so flawless it was unseen. My tentative first steps left scratches; it felt like keying a classic car. As my confidence grew, so did my speed. The sensation was irresistible, somewhere between floating, falling and, yes, flying.
In awed silence we circuited an area no bigger than a football pitch, rippling water visible beyond. As we moved, the elasticated ice reverberated with the sound of an overworked bullwhip.
It was only when hairline cracks began to appear that I thought it prudent to return to more solid ground. No one had to say it. We were skating on very thin ice.
Duncan Craig travelled as a guest of SAS (0871 226 7760; flysas.co.uk) which flies from Heathrow to Stockholm Arlanda from £135 return.
Duncan travelled to Sweden with Nature Travels (01929 503080; naturetravels.co.uk), which offers three-night "Ice Skating On Natural Ice" tours, including accommodation, equipment, meals, transfers and airport pick-up from £767pp (two sharing). Single supplement £41pp. The next tour is 23-26 January, 2014. Private tours of varying durations can be arranged until late March (conditions permitting).
Visit Sweden (020 7108 6168; visitsweden.com).