'You want me to do what?' my friend asks, before disappearing quicker than an ice block in the Sahara. She was saying no to an opportunity to make like a modern-day Tarzan. Instead of vines, there are five steel cables suspended between two mountains some 12 storeys above a raging glacial creek. Ziptrek Ecotours is responsible for this adrenalin-rush experience. It's elevated the concept of the guided forest tour and become the hottest all-weather tourist attraction at the Canadian ski resort of Whistler. The first thing we're asked to do when we book for the two-and-a-half hour Ziptrek tour is sign a liability waver. The feeling of risk this generates is probably disproportionate to the actual danger, given that two years of environmental assessment and planning preceded construction of the facilities. 'We wanted the adventure component and also a level of comfort,' says Dave Udow, who set up and runs Ziptrek. 'An accident is not an option.' After signing away our rights we're fitted with climbing harnesses. These will connect us to a pulley on a steel cable along which we'll zip at speeds of up to 80km/h. After a dummy run on a practice line, we're taken to our launching pad: Blackcomb Mountain, where the 2010 Olympic ski jump will be built. We take turns quaking at the edge of our 'where eagles dare' platform, awaiting the shove that will send us on a flight path from Blackcomb, over the white waters of Fitzsimmon Creek far below and on to Whistler Mountain. Ziptrek has no age limit, but so-called zippers must weigh no less than 30kg and no more than 125kg. Satisfied customers include a hefty five-year-old and a fit 88-year-old, says Udow. Chances are that anyone outside the weight limit will be too heavy or too light to make it across. Rain and wind can result in a pause in proceedings, so we're advised during our training to relax and enjoy the view if this happens - and wait for a guide who will climb along the cable and retrieve us. By the time we finish, we've crossed the creek from mountain to mountain five times on ziplines ranging in length from 24 to 335 metres. With every successful trip, our sense of exhilaration and confidence grow, evident in the increasing volume of chatter. Tarzan would have approved. Ziptrek ( www.ziptrek.com ) for adults (15-64) costs C$98 (HK$588); for children (under 15) and seniors, (65 and older), the cost is C$78.