It is well named, the six-hour trip allowing guests to watch as a free diver descends into frigid waters, before clambering back on board bearing the freshest possible rock lobster, scallops, sea urchin and, most of all, abalone.

Cooked in front of you and served with local wines and beers, it makes for a beguiling food adventure.

It is much more adventurous, however, for Ewen de Camp, the affable diver squeezing into his 7mm neoprene wetsuit. As we round sheer cliffs near Bruny Island, about 50km (31 miles) south of Hobart, blue skies magically appear out of nowhere – then disappear just as quickly, about 10 minutes later.

The Tasmanian weather defines unpredictable, but the cold is just one of the challenges he faces.

As de Camp is free-diving on one breath for up to two minutes, at depths down to seven metres, he dons his weights carefully.

Then he shows us the all-important white plastic gauge with which he measures the abalone underwater, to see if they are big enough to be taken.

“We catch green lip and black lip abalone in Tassie, but down here near Bruny Island we get black lip,” he says.

“The minimum-size abalone I can bring on board for you guys is this big – 138mm (5.4 inches). Trust me, there’s plenty in there.

“The point is, I can come back to this exact same spot in five years and hopefully catch an abalone just as easily. That’s why we have our catch and size limits. I might swim over 50 which are smaller, but that’s a good thing – that means it’s healthy ground for them.”

He explains that they hide away, camouflaging themselves in cracks and crevices around the sand beds, or on rocks covered in weeds. He is careful when prising them off, as a cut abalone will “bleed to death as it doesn’t congeal its blood”, says de Camp.

After his first dive, he resurfaces and holds two huge, weed-covered abalone. They are cleaned, carefully cut and then briefly tenderised in front of us.

De Camp even offers us the chance to taste tiny abalone teeth – yes, they have them – which remind me of the Spanish delicacy goose barnacles, known as percebes.

“There’s no doubt that abalone is the highlight of our Tasmanian Seafood Seduction tour,” says Robert Pennicott, the founder of Pennicott Wilderness Journeys.

“We serve it as sashimi or tenderised quick and hot with olive oil, butter, garlic, ginger and chilli and a dash of salt and pepper. But when they experience the freshest sea urchin and lobster, our guests love that, too.”

He is not wrong. Everything we consume on this seafood odyssey is sensational. It is a textbook example of taking the finest, freshest produce available and simply letting it sing.

Abalone have been around for an astonishing 500 million years and have been eaten by indigenous peoples in Australia, New Zealand, East Asia and North America for millennia. For some, it was a subsistence food because of its abundance and the relative ease of finding it.

Given the insatiable appetite for the ingredient in Chinese and other Asian cultures, however – not to mention its reputation as one of the world’s most expensive foods – its future is not looking good.

“The most immediate action people can take is to eat only farmed or sus­tainably sourced abalones,” says Dr Howard Peters, a research associate at Britain’s University of York who led the assessment of abalone for IUCN.

One restaurant, the highly regarded Été in Tokyo, headed by chef Natsuko Shoji, has already said it will refrain from serving endangered abalone species for the time being, with others expected to follow suit.

Abalone’s popularity remains undimmed, however, and China continues to be the world’s largest importer of the mollusc.

“Abalone is the symbol of wealth, prosperity and abundance,” says Wong. “Chinese culture believes that it will bring good fortune when eaten. It also has the benefits of being high in protein and combining essential vitamins and minerals.”

When choosing the finest dried abalone – and it’s fair to say that nowhere has access to finer examples than Hong Kong – Wong has very particular criteria.

“Good dried abalone has its own unique aroma. The circle area should be plump, even and complete with no black spots. When you touch it, it should feel dry, not sticky, then when you look at it under light, the body should be transparent and translucent, ideally yellow, while the heart should be brown.”

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At Forum, dried abalone is soaked in water twice until the consistency “is like soft rubber”. Once cleaned, it joins deep-fried pork ribs and chicken in a clay pot, before broth and water are added. Then three days of cooking ensue, for 10 hours a day, with more chicken broth added once it has evaporated.

Chefs use a toothpick to test the softness of each abalone, before it joins abalone sauce, superior ham stock, dark soy sauce and potato starch in a dish that is legendary among connoisseurs.

Lau has served abalone – sourced from China, Australia and South Africa – in numerous ways on Tate’s tasting menus, which meld French and Chinese cuisine, such as paired with soft steamed egg or served as a cold dish with pickled mushrooms.

“Sauces are always a highlight with abalone as, cooked with chicken, it gives depth to any dish. I love abalone’s taste of aged seafood, with layers of umami, like a good soy sauce,” she says.

“The first time I tasted Chinese-style abalone, it was too chewy and I couldn’t really understand its value,” he says. “Then I tasted Japanese abalone prepared by sushi chefs, with pure, long-lasting umami and a tender, bouncy texture.”

Abalone liver is well known among chefs for being intensely flavourful, and Arbor celebrates it in a dish inspired by its Japanese sous chef, Tsukasa Uraguchi.

“We serve abalone with a sauce made of the abalone’s own juices, abalone liver and butter,” says Räty. “Slices of abalone, fermented enoki mushrooms and crispy sourdough noodles complete the dish.”

It’s a fabulous bowl, deep and rich, decadent but not heavy, showing the remarkable versatility of this ancient and highly prized ingredient; for how much longer it can be sustainably enjoyed, however, is some­thing to chew on.