In pictures: Dean Potter in Channel 4's The Sky Walker

Climbing without ropes, throwing yourself off cliffs strapped to a parachute - you'd think Dean Potter managed to get his quota of thrills. But apparently not: here the climber is in training for his latest mountainside adventure – which is featured in Daredevils: Monday, 9pm, Channel 4. (And yes, we know he doesn't look very high up here) … Photograph: PR

But then you wouldn't be practicing slacklining high up in the sky either. Basically, it involves walking along a suspended piece of rope but - as the name suggests - instead of the rope being pulled tight, it's left slack to wobble about in the wind. Who wouldn't stay close to the ground? Photograph: PR

Well Potter, that's who. Here the ropes are being prepared for his bid to complete the longest high-line crossing ever. 'What appeals to me is the absolute focus that you need … and with that focus comes heightened awareness, where all your senses peak,' he says. Do you think heightened awareness means terror? Photograph: PR

Would you cross a canyon via only a wobbly rope? 'What appeals to me is the absolute focus you need … and with that focus comes heightened awareness, where all your senses peak,' Potter says. Photograph: PR

And so he's off. Potter learned slacklining from 'this homeless man named Chongo' whob he met in California, he says. At the time Potter had injured fingers from climbing, so started to try slacklining. Photograph: PR

'In climbing, if you injure just one finger you can't do it,' Potter says, 'But with slacklining as long as you can walk, you can walk the line.' Well, you can walk the line, Dean. Without a safety harness. We probably wouldn't try that out Photograph: PR

Most people tend to do slacklining close to the ground. Potter, clearly does not, 'If you're thousands of feet up with just a thin piece of webbing that you're standing on, it's really a sensation of being at one with the air,' he says. Photograph: PR

Potter does at least admit to getting a bit scared by the whole thing. The way he gets through that, he says, is to spend a few months being exposed to the 'big air', climbing every day, and slacklining or base jumping on his rest days. Yes, rest days … Photograph: PR

So what did Potter do to celebrate? 'I did what I usually do - take in all the beauty and just enjoy life. It's such a beautiful place up there' Photograph: PR