Around the world on a unicycle: Man takes sport to extreme lengths with incredible collection of pictures from across the globe
Trekking across the world's harshest and most remote regions sounds like a tough enough challenge - but imagine doing the whole thing on a unicycle.
Canadian Kris Holm has traversed the Great Wall of China, descended a 6000-metre volcano and braved the mountains of the Himalayas while riding on a single wheel.
As these breathtaking pictures show, he is not afraid of tackling any terrain - from perilous cliff edges to jagged mountain tops.
Vista: Kris Holm on the Moab White Rim in Utah. The brave unicyclist has crossed 14 countries and beaten some of the world's most difficult terrain Epic: An amazed Chinese man watches Holm perilously ride the side of the Great Wall of ChinaMr Holm has travelled across some of the toughest terrains in the world, including Himalayan country Bhutan and the jungles of Bolivia.
He said: 'I do get some odd looks sometimes on my travels. They know me round where I live, but abroad people do give me funny looks.
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'Some of them actually thought it was what Westerners do, ride unicycles all the time. If only that was the case.
'I have travelled on the Great Wall of China, descended down Licancabur, a 5950-metre volcano in Bolivia, and climbed the third highest mountain in North America.'
Leap of faith: Mr Holm fearlessly drops from a rock in sun-baked UtahBrave: Mr Holm on the North Shore, Canada. Such is his skill that he has even beaten two-wheeled competitors in trial competitions
Kris was the first rider to bring mountain unicycling to a mainstream audience through film, television, and magazine features. He has appeared in over 200 international media features, including numerous television segments and 18 films that have screened at festivals in over 30 countries, according to his website.
He added: 'A unicycle can go just as many places as a two-wheeled bike. Obviously over a flat distance two wheels are faster, but actually up and down hill it doesn't make that much difference.'
Amazingly, Holm, who can reach speeds of 50mph, became the first unicyclist to reach the podium in an event against his two-wheeled cousins in the gruelling seven-day mountain BC Bike Race in 2010.
Riding high: The extreme unicyclist balances on the edge of a cliff in Mexico Author: Mr Holm has written a book about his adventures called Mountain and Trials UnicyclingHe added: 'I actually finished third last year in the BC Bike Race as the only competitor among 500 riders on one wheel, that was amazing.'
Holm started uni-cycling in 1986 aged just 12 after getting the bike as a present.
He said: 'I was like any kid, I just kept practicing and soon I was riding. Learning to ride a unicycle is just like anything else it's 95 percent practice.
'Where I live in Canada there is a lot of outdoors and I love to go out on the trials, so a lot of people are used to seeing me.'
In 2010 Kris became the first unicyclist to reach the podium in 3rd place against his two-wheeled cousins in the gruelling seven-day mountain BC Bike Race Mountain king: Mr Holm in Bhutan. He designs and sells his own mountain unicycles He has helped popularise the fringe sport through his appearances in TV documentaries and features in numerous magazines'When I first started unicycling I was probably one of the only people in the world to try and ride the same trials as two-wheeled bikes but now there are more and more people willing to give it a try.
'I also design my own unicycles which are made for those who want to give trialing a go, it's a lot cheaper than mountain biking to buy a unicycle so who knows maybe more and more people will do it.'
His talents saw him scoop the 2005 European, 2002 World, and 1999 North American unicycle trials championships.
He has also written a book about his adventures, Mountain and Trials Unicycling.
Ford: Mr Holm in Monguni , Mongolia. Extreme terrain holds no fear for the Canadian, who has ridden unicycles since 1986Balance: In the mountain kingdom of Bhutan