I'm suspended horizontally, trussed up like a turkey and pointing face-first down a mile of zip wire, the longest in the northern hemisphere. And when the safety line is yanked free, there's no turning back. Zip World opened recently in the dramatic setting of the world's oldest and largest slate mine, Penrhyn Slate Quarry, by Snowdonia National Park. This picturesque corner of north Wales has long been popular with hikers, gorge walkers, cavers and climbers and now, with the record-breaking zip wire and host of other outdoor activities on offer, it's becoming known as Britain's 'heart of adventure.'
Having experimented with ridiculously unsafe home-made zip wires in my youth (or 'death slides' as we called them, with their key components including wire coat hangers and washing lines), I'm keen to test out the grown-up version, where riders can hit speeds of up to 100kmph.
But before that, I wake up early and drive to Treetop Adventures, a high ropes centre near the zip-line - it seems like a good idea to start slow with some less high-octane activities.
first up, a parachute simulator, the Powerfan Plummet. I'm instructed to climb 106ft up the Tree Top Tower. As I scale the steps I see a flock of peaceful, disinterested sheep far below, munching grass across the Conwy Valley. I've never jumped out of a plane before, but stepping to the edge of the platform, with every instinct telling me not to drop off, I imagine this is a pretty good approximation. I jump, spreading my limbs out like a deranged flying squirrel, bellowing all the way down. It's a relief not to land with a splat or regurgitate my breakfast - and I can't stop laughing.
Next, I find myself on a Sky Ride with a former operations manager for Alton Towers. As our swing is hoisted 80ft into the air, he shares that he's recently had a vasectomy, but due to the decidedly secure nature of the harness, " I needn't have bothered ". I'm still thinking of a suitable response to that when the swing is released, and I get that brilliant, stomach-dropping feeling you get from the very best rollercoaster's. But these have all just been warm ups for the main event, and it's now time to make my way past the stunning Mount Snowdon to Zip World.
After popping on a helmet and jumpsuit that's part Star Wars X-wing star fighter pilot and part Guantanamo Bay, my first port of call is the Little Zipper. A quarter of mile long, it's a gentle way to grow accustomed to flying into oblivion.
"We did have a cage fighter who chickened out of doing the Little Zipper last week. Last minute nerves," the cool, woolly hat-wearing instructor tells me.
Not sure if that's helpful or not, but after jumping out of a tree, the Little Zipper feels like a relatively tame practice run for the big one. At the bottom of the ride I join a group in their mid-20s celebrating their mate's birthday. We hop on our way up the steep, slate-strewn trail.
"On a clear day you can see the coast of Ireland and the Isle of Man from up here," says the instructor, as we wait our turn on the big drop, taking in the magnificent view across the valley and beyond.
Before I know it, it's time. Rigged up and lowered into position, the instructor makes radio calls to the control centre below, where wind speeds are constantly monitored. All is deemed well, and suddenly the safety line is pulled. I jerk into motion, reeling down the wire like a human bomb. I fly close to the edge of the state cliff and see the turquoise lake open up beneath me It's absolutely thrilling, and the minute-long ride is so smooth I just try to take it all in. I come in to land, slowed by shock absorbers on the wire, and grab the instructor's are as he reacquaints me with terra firma. That definitely beats a coat hanger and washing line, any day.