Great white hunter in South Africa's shark alley

Dun dun. Dun dun. Dun dun. Dun dun. Dun dun . . . As our boat slices through the dark emerald-blue waters of the Atlantic Ocean, off a windy Western Cape in South Africa, the theme tune of Jaws races through my head.

Forty years after the release of Steven Spielberg’s cult classic, the accompanying score, composed and conducted by John Williams, retains its chilling aura; the darting flourish of basses, cellos and trombones sending my heartbeat rocketing and prompting a swirl of butterflies in my stomach.

The sense of drama is amplified, not just from childhood memories of watching the movie (half-hiding behind my parents’ couch) but by the fact that somewhere in the water, possibly only a few metres away from us, lurks a Carcharodon carcharias — or the great white.

The catamaran vessel I’m on — a custom-built aluminium Slashfin boat — is run by Marine Dynamics, a tour operator and conservation trust that excels in getting humans up close and personal with these apex predators, which have been prowling the oceans for millions of years.

Every day dozens of thrill-seekers arrive at MD’s thatch-roofed lodge headquarters in Kleinbaai, a residential suburb of Gansbaai and a two-hour drive east of Cape Town — to sign up for a shark cage-diving adventure.

A shark approaches the cage.

Plunging into cold water with a white pointer (albeit in a supposedly “shark-proof” steel cage) didn’t appeal to me. But I’ve long been fascinated by these giants, so when I heard that you could also observe the shark-human interactions from the boat deck, I got excited.

While the neighbouring seaside town of Hermanus has been called “the whale- watching capital of the world” — due to the southern right, humpback and Bryde’s whales roaming its shores (between June and November at least) — the stretch of ocean off Gansbaai has earned the moniker “Shark Alley”.

Some West Australians may find it hard to believe, considering the number of shark sightings (and attacks) in our part of the world, but experts say this is the planet’s most densely populated zone for great whites. It’s not a seasonal thing either.

The sharks stay here all year-round, seduced by the constant supply of food. About 40,000 Cape fur seals live and breed in and around Dyer Island, the biggest in a cluster of rocky isles off Gansbaai.

The Slashfin, which accommodates 40 passengers, is one of half a dozen boats anchored in Shark Alley on this overcast autumn morning; with the various operators trying to lure the sharks closer to their vessels by “chumming” the choppy 14C waters (chum is a greasy concoction, usually of fish oil, offal and produce, that attracts the sharks). Apart from the sloshing waves the ocean seems pretty lifeless — though no one is dangling their arms and legs over the sides of the boat, just in case.

There’s actually more action in the sky right now. As well as the seals, Dyer Island is home to dozens of species of birds and flocks are hovering above us, perhaps angling for some snacks of their own.

Shark-themed souvenirs on sale near the dock at Kleinbaai.

After an hour of fruitless waiting and searching, the worry among passengers — all kitted out in wetsuits and waiting to descend into the cage beside the boat — is that we’re not going to get lucky today. A few people are even muttering about whether they’ll get a refund.

Then, right on cue, as if it’s just been toying with us, a shadow appears 10m away. Then there’s a splash. A grey fin, then a pointed nose, pierces the surface. A cry of “look” is followed by “cors”, “wows” and other unprintable words and expressions.

The energy levels on board have changed in a flash. There's excitement — and apprehension — in the air. Goosebumps prickle my skin and my heart thumps vociferously. I can only wonder what the “divers” must be feeling right now.

As the shark noses around the cage a group of six lower themselves in. The majority of the 4.5m x 2.5m cage is in the water with the top section remaining “dry”, so the divers — who aren’t wearing oxygen tanks — can come up for air. And to shout, curse and laugh — which they are wont to do when the cage is nudged and rattled.

Everyone takes their turn to go in (apart from me) and most are visibly beaming after their face-to-face encounters with the feisty 3.7m male. “I’m sure he was giving me the eye,” jokes one young British woman, teeth chattering, on the lower deck.

From my vantage point on the top deck, hands warmed by a steaming mug of hot chocolate, I get an awesome view of the shark leaping out of the water, hungrily trying to snatch a seal-shaped “decoy” cushion that a crew member has been moving around.

The shark’s agility is astonishing. And terrifying. Besides the adrenaline-packed moments — we see four more sharks, including two 2.6m juveniles — the tour also attempts to deepen passengers’ understanding of great whites with on-board wildlife biologist Helen Pattullo providing commentary about their feeding and mating habits and explaining the reality behind the myths (despite the hype, fatalities from shark attacks are incredibly rare with a reported global average of between five and 10 a year).

Great white numbers are dwindling fast, however, with an estimated 3500 remaining in the wild worldwide. Their endangered status isn’t helped by the East Asian lust for shark fin (for soups and remedies), man-made netting (sharks get fatally caught up in these barriers, notably in South Africa’s KwaZulu-Natal province around Durban) and shark culling policies (such as the controversial one launched in WA last year).

Attacking mankind’s “irrational” fear of the great white, Marine Dynamics argues that movies such as Jaws — and sensationalist media reports of shark attacks — have “subconsciously brainwashed many of us into thinking that these ocean predators are mindless man-eating monsters that will hunt, mangle and devour anything”.

Today’s tour has certainly softened my view towards these majestic creatures and it’s tragic to think they could become extinct in a generation or a two (not least for the oceanic eco-system in which they play a vital role).

Truth be told, despite the positive feedback from today’s cage divers, I still have no great appetite to share the chilly sea with these mighty fish, which can grow up to 6m long and weigh over 2000kg. But being able to marvel at them from the (dry) deck of a boat is a spine- tingling treat.

FACT FILE

Marine Dynamics run daily shark cage-diving trips, priced at 1600 rand ($170) for adults and 950 rand ($100) for children under 12. This includes breakfast and lunch at their Kleinbaai office and on-board snacks. Shuttle bus transfers from Cape Town are 400 rand ($42); sharkwatchsa.com. For more information on touring Cape Town and the Western Cape, see capetown.travel.