Fancy skating across a frozen lake in Outer Mongolia? Or how about taking part in a race across the Namibian desert - or hacking through the jungles of Panama from the Atlantic to the Pacific coast? Then York-based rat Race Adventure Sports could be for you. STEPHEN LEWIS gets ready for some adventure...

IT IS cold in northern Mongolia in January - as low as -47 degrees at night, rising to a mere -30 as the sun rises in the sky during the day.

The waters of the Khövsgöl Nuur - a lake at the northern edge of Outer Mongolia - freeze solid, the ice up to a metre thick. As the temperature rises during the day, the ice flexes and groans, creating extraordinary sounds.

"You can hear it going off all around you like a 21-gun salute," says adventurer Jim Mee, who has just returned from an expedition where he skated from one end of the lake to the other. "If you lie down on the ice, you can hear and feel it." Not that you'd want to spend long lying on the ice in those temperatures...

Outer Mongolia is on the southern edge of Siberia. Khövsgöl Nuur, the lake Jim skated across, is fringed by snow forests of larch and pine, which are home to packs of wolves. At night, Jim and his companions would camp in traditional Mongolian gers - the round, felt-covered tents we know as yurts.

They had log-burning stoves where they'd cook wild boar and reindeer freshly sourced from the forest. "And we'd go to sleep every night with the sound of wolves howling from the nearby treeline," he says. Luckily, the region's native brown bears were still hibernating...

Jim, the 40-year-old founder of York-based Rat Race Adventure Sports, was in Mongolia to suss out a new adventure challenge which the company will be offering to paying punters from next year.

He and the other seven members of his expedition set themselves a simple challenge - to cover the 100-mile length of Khövsgöl Nuur 'by any means'.

They flew to Ulaanbaatar, the capital of Outer Mongolia, and there took a charter flight to the Mongolian town of Murun, where they were met by their Mongolian guides - on horseback, but also with an ancient diesel vehicle the expedition dubbed the 'Russian fun-bus'. "You had to apply a blowtorch under the truck to warm the diesel to get it going - but then you could drive it anywhere!" says father-of-two Jim, who lives with his family at Kilburn.

The fun-bus, plus two accompanying 4x4s, were the expedition's back-up. But, while the locals happily use Khövsgöl Nuur as a convenient north-south highway when it freezes in winter, Jim and his companions were determined to make the crossing under their own steam: him on skates, his colleagues running or travelling by bicycle.

Skiing would have been impossible, Jim says. The air of Mongolia is bone dry - so there's no precipitation, no rain or snow. Without snow, skis would be useless.

Nevertheless, the experienced skiier was able to use the skills he'd learned to quickly adapt to skates. He and his companions were able to make the crossing from one end of the lake to the other in just three days.

It wasn't always easy going, he admits. The ice that covers the surface of Khövsgöl Nuur is seamed and cracked and plated, because of the way it forms. There are ridges and rough areas, which sometimes required lengthy detours. That's why, even though the lake is only 85 miles long, they reckon they covered a distance of 100 miles in the three days.

The main challenge was the bitter cold. There's a reason why the locals wear fox-fur hats and traditional long winter coats - they're great for keeping you warm, Jim says. They had wood-burning stoves in the gers to keep warm at night. But going to the loo was a problem. The thought of exposing yourself to temperatures of -47 degrees just to empty your bladder was so off-putting that often they'd use a bottle instead, Jim admits.

They did the same during the day. Khövsgöl Nuur is a sacred lake - and also the region's only source of fresh water. Using it to go to the toilet is taboo. So they'd use bottles, which they'd then have to carry with them to dispose of safely. The bottles would quickly freeze in the icy air. "So you'd end up carrying these ice boxes of wee down your jacket every day," he says.

There were compensations for the discomfort, however. Because of the clear, dry air, sunrises and sunsets were spectacular. And because of the lack of light pollution, at night the sky burned with stars. "You could see every star in the sky," Jim says.

The waters of the lake are wonderfully pure - which meant the ice was too. "You could look down between your feet and see for many metres into the water below the ice," Jim says. "It's disconcerting, but ultimately beautiful."

Near the lakeshore, meanwhile, they saw something even more extraordinary - frozen waves. Not just ripples. "These were big breakers that had frozen."

One of the most surreal experiences happened on their second night, when they camped on a small island in the centre of the lake. A shaman from a local tribe of reindeer herders came to 'bless' their expedition.

She had clearly taken some kind of hallucinogen, Jim says. The ritual began with drums, and proceeded to weird shrieks and screams, while the shaman flung her body about, before eventually throwing herself on the fire.

No one was hurt. "But it was definitely eerie," Jim says.

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Rat Race Adventure Sports, which is based in Shipton-by-Beningbrough, has been running adventure sports challenges for paying punters, mainly in the UK, since 2004. It is now planning to offer a series of new 'bucket list' challenges in remote and exotic corners of the Earth. The Rat Race Mongol 100, which will be the first of these, is planned for March next year. Those taking part will be invited to cross the length of the frozen Khövsgöl Nuur 'by any means' - walking, running, by bike or on skates.

There will be back-up teams to provide support and to carry the gers - and, just in case, to keep the wolves away - just as there were with Jim's original expedition.

But make no mistake, the challenge - which is likely to cost about £2,500 per person to join - won't be a picnic.

"It is not supposed to be some epic suffer-fest, and it won't be dangerous, we'll make sure of that," Jim says. "But it will still be a tough challenge."

Other challenges in Rat Race's new bucket list series will include a 'Race to the Wreck' across the deserts of Namibia in south west Africa which will finish at a famous shipwreck off the Skeleton Coast; and a challenge to cross the isthmus of Panama in central America, from the Atlantic to the Pacific cost. The route of The canal challenge will roughly parallel that of the Panama Canal - but it will take in impenetrable jungle, as well as crocodile-infested rivers and lakes. "Make no mistake, this is a real adventure," says Jim - who, naturally, has already been to Panama to suss out the route.

BLOB To find out more about the Mongol 100 and other challenges on Rat Race's 'bucket list' series, visit ratrace.com/