If you want to draw attention to yourself in Oban, tell the locals you're planning to swim across the Corryvreckan whirlpool. It certainly gets the attention of my cab driver, who almost crashes the car when I tell him my plans. "You're going to swim the Corryvreckan?" he repeats incredulously. "My God! Have you seen it?"
The next day, as I prepare to jump into the formidable-looking body of water, his reaction makes a lot of sense. For one thing, Corryvreckan is looking a lot more whirlpool-like than I'd been anticipating when I planned my trip from the comfort of my living room. The water is bucking and rolling in a truly alarming manner.
The worried tones of Peter, the pilot of our tiny boat, aren't helping either. "You've only got half an hour before the tide changes, so you're just going to have to go as quickly as you can. Don't stop. Put your head down and go." I leap over the side like a porpoise on a space hopper and start swimming as if my life depends on it.
A tad overdramatic? Perhaps. But then, this is a stretch of water with a terrifying reputation. The mile-wide strait of locally notorious water that separates Jura from Scarba in the Inner Hebrides is said to be one of the largest whirlpools in the world. It is also said that the Royal Navy classifies it as officially "unnavigable". The whirlpool's most famous victim is undoubtedly George Orwell, who was shipwrecked here while staying on Jura to write 1984.
So why swim in such a treacherous place? Blame the recent craze for "wild" swimming. Once the preserve of a few hardy enthusiasts, today there are books (such as Daniel Start's Wild Swimming), television shows (Alice Roberts' Wild Swimming for BBC4), organised charity events (including the hugely popular Great Swim events) and reams of media coverage dedicated to this flourishing new sport.
Kate Rew, author of Wild Swim, runs the Outdoor Swimming Society and thinks that the desire to experience the freedom of outdoor swimming has always been there. "I think all people really needed was the idea of it: of becoming an opportunistic swimmer, a swim tourist, who takes the plunge not just in places they know, at expected times or seasons, but wherever they go."
The holiday company SwimTrek, which organised my Corryvreckan swim, is another reason why the movement has gained such momentum. Run by Channel swimmer Simon Murie, it runs guided swimming trips all over Europe, from frigid dips in Finnish lakes to balmy missions in the Greek islands. Then there are the popular one-off event swims such as Alcatraz, the Dardanelles strait in Turkey – and the Corryvreckan. Mexico's Baja peninsula and the British Virgin Islands are also on the firm's agenda.
My initiation into the world of wild swimming came in 2007, when I swam across the Dardanelles, the channel that separates Asia from Europe. I'd been inspired by Lord Byron, official patron saint of all wild swimmers and the first man to swim the stretch of water back in 1810.
After battling my way across in a respectable 75 minutes, I was hooked. Soon I began to look for other similar challenges – which is how I eventually found myself in a tiny boat, bobbing around in the boisterous Corryvreckan. Mine is a familiar story among wild swimmers, I learn from my fellow whirlpool tamers. Graham, a local, swims in the sea each day and has been building up to take on Corryvreckan for years. Diana and Jennifer are using it as part of their preparation for a cross-Channel relay swim during the summer. The tension is palpable as we listen to our pre-trip briefing.
The Corryvreckan owes its unpredictable nature to some unique underwater topography and strong currents that race through these features from the Atlantic. As the water rushes forth, the tide swiftly reaches a speed of 8.5 knots and produces the violent waves, whorls and whirls that can toss boats around at will. That's why we're going to cross at slack tide, when the flow of water is at its calmest. It's the only safe time.
It all sounds fine on dry land, but my heart is pounding as Peter talks us through it all. And that's before I've even immersed my head beneath the icy waves, usually the main threat to an open-water swimmer's short-term health. Sure enough, as soon as I hit the water, I experience the reflex action that anybody who has experienced a cold shower knows all too well. My heart starts racing; my throat instantly tightens and my breathing becomes laboured and forced.
It's not the ideal start, especially as we've had it drummed into us that we have to complete the swim in 30 minutes if we're to beat the changing tide. For the first 50 or so yards, I have to battle a rising sense of panic, something also caused by a slightly eerie feeling I usually experience at the beginning of any open-water swim, a primordial fear of nameless deep-sea monsters nagging at the back of the subconscious.
Soon, though, my breathing is under control and I can relax and begin to enjoy the challenge of battling the current and waves. After 25 minutes, I look up and see land looming close. I'm going to make it.
The swim over, I clamber back into the pilot boat and gratefully grab a cup of tea. I'm shaking, a combination of tiredness, adrenalin and endorphins. True, at 31 minutes, I'm just outside the half hour target time I had set myself, but it is an amazing feeling to accomplish a goal that I've been working towards for the past few months. I'm almost ready for the next one.
SwimTrek (01273 739713; swimtrek.com) offers escorted trips to swim Corryvreckan (3-15 August) from £90pp including an acclimatisation swim. Hotel/travel extra.