On a wing and a pair of shoelaces

Kev is not happy. He's gripping the handrail so hard his knuckles have turned white. "You're all right mate," says Ged reassuringly as he attempts to lure him towards the edge. "No, I'm bloody not," Kev spits back through gritted teeth. In a heart-warming display of compassion, the rest of us fall about laughing. It's amazing just how amusing someone else's discomfort can be.

The cause of Kev's unease is twofold. First, we're perched on a narrow metal platform 23 metres above the forest floor. Second, we're faced with the prospect of traversing a 214-metre zipline supported by what look suspiciously like a pair of shoelaces. Kev - as you might have guessed - is not a big fan of heights.

Hollybank Treetops Adventure opened in January last year and already more than 8000 people have completed the course of seven ziplines that zigzag between metal platforms called cloud stations high up in the forest canopy. Interestingly, many people come specifically to conquer their fear of heights and only 20 have had to be evacuated after deciding they can't carry on (this may well be because the evacuation process involves being slowly lowered from the middle of a zipline, which sounds far scarier than finishing the course).

Our three-hour tour started with a comprehensive safety briefing from our two entertaining guides - Ged and Tillsy - during which we were fitted with helmets and safety harnesses. Apparently, the flimsy shoelace-resembling cords that will be supporting us can each bear more than two tonnes, which is exactly the sort of hard-to-believe but reassuring-to-hear fact you want to know before you put your life in their hands.

The first couple of flights are relatively tame but we quickly gain altitude as we head out over the valley. After the third zipline, I look down to discover we're buttock-clenchingly high up a worryingly narrow tree. Tillsy cheerfully tells us the next flight is a great shot for a photo and recommends we let go of the ropes and lie back in our harness with our arms and legs spread-eagled. Kev is not keen.

The best flight is the last: a soaring 370-metre trip over the Pipers River. It's an exhilarating rush, hurtling through the forest at 60kmh, 50 metres off the ground, trees flashing by in a blur.

At the end of the tour we're like a bunch of overexcited children. "Again, again, again," we all chant. Well, almost all of us. Kev was last seen stumbling towards the car. Still not happy but certainly relieved.