“These guys don’t make any noise, so don’t expect them to come with Jaws music. Great white sharks are the ultimate ambush predators: you’ll see nothing then suddenly they’re in your face.”

Boat skipper Kim Shepperd is briefing 20 visitors before they’re submerged in a steel cage.

“And don’t stick your arm out the cage! Not because you’ll get it bitten, but because some of these boys weigh over a ton. If he brushes your arm, that’s your arm broken and it’s a three-hour trip to get you back to Port Lincoln.”

These visitors have come from all over the world to put themselves into what many would consider a compromising position. Two have come from New York, one from Toronto, deliberately detouring from their eastern-states itineraries to be anchored off two bumps in the Southern Ocean called the Neptune Islands.

Travelling out on a limb

“We just had to do it,” says one of the New Yorkers. “We looked at doing it here and in South Africa. And we chose here. This is it, man!”

Last year three operations helped bring Port Lincoln to the attention of Australia and the world through shark diving experiences.

Adventure Bay Charters, as well as Rodney Fox Shark Expeditions and Calypso Star Charters , generated an estimated $12m for the Eyre Peninsula economy. Not bad for a region with only 59,000 people, one that was virtually unknown 20 years ago.

Eyre Peninsula – along with its far-flung, frontier-like capital, Port Lincoln – has steadily affirmed itself as an adventure destination, a wild place where visitors can have close underwater encounters with the like of great whites, dolphins, sea lions and tuna.

There was a setback last year when the swim with the tuna operation closed, the owner intending to shift the huge floating tuna pond (with tuna) closer to Adelaide.

But that hasn’t stopped the region moving forward in 2016 to offer fresh Eyre product and even closer encounters.

Adventure Bay Charters has innovated with the use of music speakers lowered into the water: when AC/DC, Tone L?c and Black Sabbath are blasted into the water, the great whites come a-calling (a method that leaves the operator less open to criticism for attracting lethal predators with the promise of a feed).

Now owner Matt Waller has also modified his already impressive dive boat with a submersible pod.

Once moored off the Neptunes, the skipper lowers the glass-walled pod to sit immediately behind the cage.

When I’m not in the water (and you can spend as long as you like) I’m very happy in the glass tank nursing a beer. It’s like a gallery, and an audience of six can enjoy all the underwater action – not to mention the muffled strains of AC/DC, Tone L?c, Black Sabbath et al.

Alas, however, my luck isn’t in because neither are the sharks.

It is a full 12-hour experience, guests are well-fed and the vibe is akin to a lively fishing expedition with the crew tirelessly trying to hustle up the infamous deep-water residents.

After my day on the boat I find guests are quite resigned to having not seen their quarry, but feel they’ve had a fulfilling and fun day. It’s a happy boat.