Surely this is going to hurt. I'm standing at the top of a two-storey drop into swirling seas, and I've got no choice but to jump. Treading water below me is the rest of my group, their arms and legs working away frantically like little ants caught in a puddle.
"If any of you don't want to jump, you can always walk around," says our instructor, Steve, with just the slightest raise of one eyebrow. Under any other circumstances I'd have no qualms in immediately taking him up on his offer. The trouble is, the rest of the guys in my group are all here on a stag do and the testosterone is flowing. There's no room for wusses here - and the bloke in me is forced to rise to the occasion.
While most people would refer to what I am about to do as madness, it actually has a name: "Coasteering". It is the shoreline cousin to the increasingly popular city activity of "parkour" - the art of getting from A to B by negotiating the obstacles in your path. The aim of coasteering is to work your way along the coast by any means necessary. That means swimming, scrabbling, climbing and, unfortunately for me, leaping off cliffs.
So here I am, in coastal Jersey. Pretty damn petrified, to be honest. But I have no option. So I switch myself onto autopilot, go against my body's instinct for self-preservation and step into thin air. I fall for what seems like minutes, before letting out a feeble little moan as I crash into the blue.
Seconds later, I come up in a rush of air bubbles and adrenalin - itching to do it all over again. The older you get, the harder it is to push yourself beyond your comfort zone. But the rewards are enormous. With this first jump out of the way, I feel like I could tackle anything. As each of us in the group takes a leap of faith, the rest of the boys urge us on with collective cheers. I've only known them for half-an-hour, but the sense of camaraderie has made me feel part of a team already.
"We grew up doing things like this," says 30-year-old Simon, from nearby Guernsey. "We'd spend the whole day scrambling about over rocks and launching ourselves off the highest point we could get to."
Having got our breaths back, we follow Steve on to our next obstacle - a cliff-face about 100 metres away. This involves swimming across a small stretch of open water, which I would never normally consider in this country.
Togged up in wetsuit, buoyancy aid and helmet, however, I hardly notice the cold. No annoying swimming lanes to stick to, no clocks to watch and no lengths to count; you simply aim for the next point and get there in your own sweet time.
We arrive at a cluster of black rocks, with the rubbery smell of Neoprene and sea salt mingling on the breeze.
As someone who gets sweaty palms from climbing a stepladder, I'm not overly keen on the idea of hauling myself up a cliff. Buoyed by a new-found confidence, however, I set off towards the top without even thinking.
Throughout the remainder of our two-hour amphibious adventure, Steve has us going higher than I would ever normally consider. It's certainly not something that could or should ever be undertaken without a guide. However, it's not all about heights. At one point, he leads us through an underwater hole in order to access a cave most tourists generally miss out on because of its submarine entrance.
I dip below the surface, open my eyes and follow a blue light that leads me safely to the other side - an experience that reminds me of a scene from Eighties undersea thriller, The Abyss.
For someone seeking for a "point" to this slightly bonkers sport: this is it. We've arrived in a hidden cave that's as exotic-looking as anything you'll find in Thailand or Indonesia. Turquoise water slaps gently against the surrounding rocks, light reflections dancing on the ceiling like strands of fairy lights.
By the time we wash back up on the beach, it feels like I've been on a real expedition. This is a side of Jersey that I was not expecting to find. Prior to coming here I'd envisaged busloads of cotton wool-haired grannies and legions of toddlers armed with buckets and spades. The reality is more contemporary. Smart hotels and eateries have sprung up all over the island, most of them using ingredients that are caught off (or grown on) the island. After washing the sand out of my ears back at the hotel in St Helier, I head around the corner to the Michelin-starred restaurant, Bohemia.
With its chocolate-coloured wood panelling, smart leather chairs and cream tablecloths, there's an air of sophistication about the place that stops shy of snobbery, thanks to the refreshingly friendly staff. The menu, meanwhile, is an interesting blend of French and English - with frogs' legs sitting on my plate alongside minted peas.
The next day, after grabbing a rental bike, I cruise along the coast for a couple of miles before heading inland to the Jersey War Tunnels Museum - formerly known as Höhlgangsanlage 8. For almost three years during the Second World War, islanders and imported slave workers from North Africa, the Ukraine and Russia, along with thousands of European Jews, toiled away inside the bowels of the island, shifting thousands of tonnes of rock in order to construct a bomb-proof concrete labyrinth that stretched for over a kilometre. Most of the men and women who worked here perished from starvation and exhaustion, and the museum serves as a reminder of the atrocities that took place.
As we shuffle along the chilly corridors, our echoing footsteps are accompanied by creepy recordings of Nazi soldiers barking orders; it doesn't take much imagination to work out how terrible the conditions must have been. The contrast between these dark tunnels and the beauty of the hidden, magical pool we'd visited the day before was all the more stark.
The writer travelled as a guest of Crystal Active (0870 402 0291; www.crystalactive.co.uk) which offers various packages to Jersey, running between March and October.
Prices start at £210 for three nights, including flights and B&B accommodation, plus a free activity. You can fly to Jersey on a wide range of airlines.
For information on coasteering and other Jersey adventure activities, contact Pure Adventure (01534 638 888; www.purejersey.com).Reuse content