Swimming with wild dolphins is one thing, singing with them requires another skill altogether, writes Kerry van der Jagt.
Swimming with dolphins sounded like child's play, until I heard I would be attached to a harness, clipped to a towrope, and dragged face first through the water beneath a catamaran.
But first there was the net to negotiate, a bouncing cobweb stretched across the bow, from where we would enter the water. Slung in the mesh like the day's fresh catch, hands welded to the webbing and teeth snapped like a clam on to the snorkel, I wait for the call. "One, two, three. Go," shouts divemaster Adam, dropping the net and setting us free. Simultaneously, five of us plop into the heaving ocean, spin around and lunge for the rope stretched between the twin hulls of Imagine.
With a thumbs-up we are away, goggles submerged, arms stretched tight and legs flapping behind like washing on a clothesline. At first I can see only bubbles and flailing limbs, then, as we gradually settle into a rhythm, torpedoes appear. Shards of sunlight penetrate the water to reveal dozens of dolphins, spinning, leaping and flying on all sides, some turning their heads to make eye contact before rocketing away. 
Then it hits me - I'm not swimming with dolphins, they are swimming with me.
I'm two kilometres offshore of Nelson Bay in the Port Stephens-Great Lakes Marine Park when the flash mob appears. Using echolocation and super-sonic vision, this pod of pranksters has come to see what the funny humans are up to.
While dolphins have an evolutionary history going back 50 million years, when their hoofed, wolf-like ancestors made the bold return to the sea, humans appeared relatively recently, between five and seven million years ago. And our lack of grace in the water shows.
In response to the dolphin's highly developed squeaks and creaks, a sonar system that still baffles NASA, I send out a series of "toot-toot-toots". We'd been advised to sing, but caught in the moment, the only sound I muster is a honking noise, not unlike a three-year-old with a party horn. Forget the spiritual side of swimming with dolphins; this is just sheer, unbridled fun.
All too soon I'm back on deck, letting the next group prepare for their swim. In the interim, while Imagine is stopped short, a pod of 40 to 50 dolphins gathers around, sullen, like children when the merry-go-round has stopped. "Hurry up, guys," they seem to be saying. "Get back in the water."
Our morning had begun before dawn, slipping on wetsuits in the dark and motoring out of Port Stephens harbour as the sun broke the horizon. With harnesses and snorkels fitted, a light breakfast served and safety talk out of the way we gather on deck to listen to Adam Wiltshire, divemaster and manager of Dolphin Swim Australia, talk about the short-beaked common dolphins we will be swimming with.
"We think they migrate somewhere between Sydney and Byron Bay," he says, his arm sweeping across the blue.
Adam explains that these common dolphins, with their hourglass-shaped capes of grey, gold and white, are different from the all-grey Indo-Pacific bottlenose dolphins found within the bay.
"The resident bottlenose dolphins, of which there are about 90 individuals, stay in the bay all year round," explains Adam, who has worked for the last two years on updating a population census while completing his Environmental Science degree.
"But no one knows much about the common dolphins in the open water," he says. "So far we've identified 400 individuals using cameras fitted underneath Imagine's hulls, but there are thousands of dolphins out here."
It took Dolphin Swim Australia's chief executive, Andrew Parker, four years and two applications to receive a permit from Marine Parks Authority to offer his world-first, wild dolphin swimming tours.
Dolphin Swim Australia's commitment to research, conservation, education and long-term population studies is the backbone to the company's ethos.
"The idea came to me in a dream," says Parker, a divemaster, marine mammal observer, rescue diver and instructor. "I dreamt of helping children with autism by getting them into the water with wild dolphins."
Enlisting the help of experts such as psychologist Dr Olivia De Bergerac, author of The Dolphin Within, and his mate, Frank, the skipper of Imagine, Parker began using "dolphin-assisted therapy" with children who have autism, cerebral palsy, Down syndrome and cancer.
"The first time we put the kids in the water, one of the mother dolphins brought her baby over to show us," he says. "When I saw the looks on the children's faces, I knew this was what I wanted to do."
After our first swim, Adam regales us with stories about other such dolphin encounters, such as the games they play, like passing pieces of seaweed to one another.
"I've even seen a dolphin try to pass some reed to one of our swimmers," he says.
And it doesn't stop there. Time is on our side and we are hopeful of a second swim. The skipper heads in another direction, giving a wide berth to a feeding frenzy signalled by a flock of terns dive-bombing a concentrated area.
"Dolphin pods work together to drive a shoal of fish into a whirlpool," he explains. "If we disturb them, we will have wasted the energy they've put into building the bait ball."
Minutes later the sky goes dark, as if someone has thrown a grey rug over the world. The wind drops and the ocean flattens, the fog pressing down, its weight an unwelcome intruder, silencing all conversation and crippling our spirits. All eyes turn to Frank as he manoeuvres Imagine through the gloom, the groan of a rope and the lapping of water the only sounds.
Finally, the sun breaks, sending great waves of light cresting over the water, light that is now bouncing off the arched backs of the carnival of dolphins heading our way. This time I negotiate the net like a trapeze artist, connect my harness and leap like a lemming on the count of three. It is child's play after all.
GETTING THERE
Port Stephens is 2.5 hours from Sydney; take the M1 freeway past Newcastle and follow signs to Nelson Bay.
STAYING THERE
The Nelson Resort is a two-minute walk to Dock C, d'Albora Marina, where the dolphin swim departs. Garden view queen rooms start from $190a night. Phone (02) 4916 4600, see nelsonresort.com.au.
SWIMMING THERE - WITH DOLPHINS
The Eco Certified tour operates Fridays to Mondays from   September to   May. Cost $289 a swimmer; $60 for non-swimmers. Phone 1300 721 358, see dolphinswimaustralia.com.au.
Kerry van der Jagt was a guest of Destination Port Stephens.
TRIP NOTES
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INFORMATION
portstephens.org.au