Maybe it's because we're becoming frustrated and bored by our safe, couch-potato lives; or perhaps there's some deeper Freudian psychology going on. But Britain's going mad for near-death (but Health and Safety-approved) indoor "experiences".
Yesterday saw the launch of what is being sold as the scariest adrenalin rush ever offered to the public anywhere in the world - a 160ft, £50-a-go indoor bungee jump in a darkened derelict steel mill near Sheffield.
Last week, it was an indoor skydiving experience in Milton Keynes where, for £33, shoppers can liven up their day by stepping into a wind tunnel that replicates jumping out of a plane and plummeting groundwards at 170mph.
Such attractions are opening monthly. Almost anything designed to exploit or defy old Mr Gravity - skiing, rock climbing, being turned into a human catapult - will do, so long as it's indoors (in case of rain) and accompanied by a dizzying range of fast-food opportunities.
Now, I am no danger-junkie. My idea of risk-taking generally stops at having an overdue library book. But I still admit to having a weird, illogical attitude to physical danger. I can fly - and indeed have flown - in anything from gliders to vintage aircraft, but heights without the benefit of a flying machine, I don't like one bit.
This week, however, in just a single day of uncharacteristic derring-do, I stepped off a precarious platform the height a 14-storey building, climbed halfway up a 15-metre wall of ice, and went skydiving. This is how anyone with a set of wheels and a wallet reasonably full of cash can enjoy a full day of horrifying experiences in 21st-century Britain's leisure centres of fear...
"Detached retinas, ruptured aorta, buggered back. I can't advise you too strongly not to do this," said Graeme. "You're seriously going to leap into thin air from 160ft up? That's the height of a sizeable office block." Strong words - and worth heeding, as Graeme is one of Britain's most prominent scuba divers.
When I get to the Magna Science Centre, a magnificent post-industrial use of a decaying old steelworks, Jon Snape of the UK Bungee Club is superbly reassuring. "In 13 years of organising bungee jumps, we haven't had a single injury or mishap," he says. "The most dangerous sport statistically is lawn bowling, with fly fishing second. Bungee jumping doesn't even figure on the list."
What about the ruptured aortas and whatnot? According to Jon, there are two types of bungee cord, and they only use the natural rubber type. It's the others - called shock cords, apparently - that cause a few problems. OK.
I wonder, as this is meant to be safer than bowls, why I'm having to sign a "dangerous activity" waiver and, for that matter, why £15 of the £50 fee (non-refundable for those who wimp out) is for insurance. Obviously, the boys at Lloyd's don't have Jon's faith in the safety of bungee jumping. If I were a year older than 50, I see, I'd need a doctor's letter to do this.
Preparing is a bit like being prepped for execution. Your spectacles, watch, phone, keys and belt are removed, to be replaced with strange corset-like garments. The bungee cord is most reassuring, fully 3in thick and made of thousands of strands of elastic. It looks like it's from some macho outdoor sports workshop in Colorado. Er, no, says Rob the jump master, they make 'em themselves. "So this is, like, knicker elastic from a haberdasher's?" I quaver. "Well, not exactly from a haberdasher's, but yeah, it is elastic."
We take a trip up the 143 steps to the gantry. The void below is beyond imagining. If anything, the hype about The Abyss has been underplayed. To my eyes, a person standing at the bottom looks about half a centimetre tall. To add to the horror, the loud music (I will never feel the same about the Foo Fighters), the dodgy disco lighting, the smoke and the ghoulish, scary wooden death statues gurning up at you from the distant floor are all distinctly unhelpful to instinctive cowards.
Oh, and you can't see the landing site from the gantry, which is oddly off-putting, as it's hardly a safe refuge - it's just a patch of greengrocer's grass rolled out over the concrete floor.
"The fear is all in the perception," explains Jon. "We're selling adrenalin and fear. So far, we've had a 10 to 15 per cent refusal rate, which is 10 times that for outdoor jumps. This is the only one of its kind in the world, and even experienced jumpers are finding that it's like learning a whole new thing."
At this point, one of the lads who's been painting the gantry for its grand opening does the jump. Only then do I realise that the initial 2.5-second plummet down from 160ft to just 12ft is only part of the deal; you then oscillate up and down for two or three minutes, hanging upside down like a demented bat. The first of such rebounds takes you almost back up to where you started.
I pray silently to a deity I don't believe in, think of my loved ones, think of Roger McGough's poem "Let Me Die a Young Man's Death". I check my pulse - 156; high, but no higher than I get before the dentist's drill.
Bizarrely, as I'm considering that fact, I let go from 160ft above a landing site I can't see. They say I shouted something that I meant to be "Geronimo", but it came out more like "Wooargh!" You're meant to fall in a graceful swallow-dive, but mine felt as if it looked more like a chicken dive. I can't remember seeing or hearing anything. It was oddly silent and lonely. The major sensation is not the feeling of falling at 50mph, but that of a brisk breeze. That, I think, is the last thing suicides must feel.
Such gloomy thoughts evaporate when it becomes apparent that I am neither dead nor hurt. The bouncing up and down thing, during which you achieve weightlessness several times, is positively joyful, and the whole experience massively confidence-building. If you can do this, you can do anything.
The Abyss, Magna Science Adventure Centre, Rotherham (01709 720 002; www.visitmagna.co.uk)
The Xscape centre at Castleford, near Leeds, is the feature of my day of death defying to which I have given the least thought. It is also Arthur Scargill's worst nightmare - a gargantuan pleasure dome chock full of international brands, built on the site of a defunct coal mine.
I've watched ice climbing on television and in the film Touching the Void without having any idea of how it's done or, really, why it's done. This is not through lack of curiosity; I just never imagined that I'd ever have the slightest opportunity to try it. Why would you, if you weren't in the habit of hanging about at the top of mountains?
And therein lies the genius of the modern indoor experience genre. One minute you're shopping and guzzling pizza, the next, you're in a giant freezer, where it's minus 6C, done up in full-on ice-climbing gear, ice axes in hand, contemplating a 48ft, 300-tonne wall of ice - the biggest in Europe and tougher than anything on a mountain - and all this with your former fellow-shoppers peering at you through the glass.
Real ice climbers use the Toyota Ice Wall to practise; one has scaled the fl height in 14.6 seconds. Since I previously didn't know a crampon from a screwgate belaying device from a carabiner, I am a little slower, managing to get to 15ft or so in five minutes with immense, unbelievable effort on my part, and patience on the instructor Dan Garland's.
Ice climbing turns out to be unexpectedly scary and not remotely pleasant. But the sense of achievement in learning a new skill and putting it to the test - however cack-handedly - in less than an hour, was quite shocking. It's no picnic, but it's vastly more interesting and challenging than any gym. And if the aches it leaves as a souvenir are anything to go by, just as good as exercise, if not better.
I most certainly shan't be going ice climbing for real in this or any other life. But I now know how to ice climb, and I've done it, which is worth a few quid of anyone's money.
The Toyota Ice Wall, Xscape Castleford (01977 516774; www.xscape. co.uk). Climbs cost from £15 to £40
Airkix ("It's where people fly"), just opened for business in a Milton Keynes leisure mall, seems the most benign of my day of near-death experiences. But then it occurs to me that the "killed in a skydiving incident" or even "lost in an ice-climbing tragedy" have more of an authentic ring to them than "killed in a bungee-jumping disaster".
So here, too, there's a "statement of risk" to sign acknowledging that you accept that simulated freefall has "an inherent danger and risk of injury due to the very nature of the activity". Airkix consists of a straight-sided goldfish bowl 9ft in diameter by 24ft high, in which one to four people at a time enter to be blasted from beneath by a 170mph torrent of air created by four 250-horsepower fans.
"Flying" requires a detailed tutorial and classroom practice first. There is a series of hand signals to learn and a complicated Nasa-style protective suit to get yourself into. Once we are in the tank, we enter one by one for two two-minute flights. This is as much as a beginner can handle. Watching fellow students fly is like seeing bumble bees in a jar. There seems to be no logic to controlling your flight. You bob up and down wildly, with an instructor in with you signalling how to achieve a steady, stable arched back flight.
My first attempt was a disaster, me thrashing about with the grace and coordination of a giraffe trying to dive off the top board. I completely forgot what the hand signals meant. But it still felt the most exhilarating thing I've ever done. Some of the staff call Airkix "the smile machine", and it's hard not to grin.
The wind is extremely powerful and does strange things to the jowls of chaps of a certain age. My second flight was fantastic, although still shameful in comparison to that of a 12-year-old lad who looked like Spiderman in training. Seeing two expert skydivers do a demonstration at the end was an eye-opener too; they resembled nothing less than two astonishingly nimble stunt-goldfish.
Airkix freefall wind tunnel, Xscape Centre, Milton Keynes, 0845 331 6549, www.airkix.comReuse content