There are two important items the novice snorkeller requires when venturing into the Coral Sea to observe underwater life. One is a marine biologist who oozes knowledge, builds confidence in the novice and instils in them the utmost feeling of trust and willpower.
The other item is a long, tubular floaty thing that helps one remain buoyant during times of staggering wonderment and blind panic.
Quicksilver was kind enough to offer my sister and I (neither of us spring chickens) the opportunity to travel on its turbo-powered boat that whisks people to the edge of the continental shelf off the Queensland Coast, for an in-your-face encounter with the underwater world.
Leaving Port Douglas to the outer edge of the Great Barrier Reef, my sister and I help ourselves to a lovely morning tea on board, before inspecting the decks. Leaning carefully over the back of the boat, we watch as the turbo engines churn white water like an atomic washing machine.
John is one of our on-board marine biologists and will soon be my trusted expert snorkeller. He talks the passengers through a visual presentation, outlining the species we should see.
He alerts us to the rules of being witness to this marine park and the perils to us, and marine life, if these rules aren't observed.
"I grew up in Chicago, shipped myself off to Jamaica, studied marine biology and never looked back," John tells me. "You really have to study hard and be top of your class if you want to be a marine biologist. I was able to do that."
Finishing his studies, but unable to find suitable employment, John launched his own successful business in Los Angeles. "I started a marine bio-medical research company and did really well. I bought a yacht, sailed around the world and ... here I am," he smiles.
The Great Barrier Reef extends for 2300km along the northeastern coast of Australia, with Agincourt Reef being part of a network of about 2900 individual reefs. John explains that corals are animals in the same family as jellyfish but made of a solid skeleton. We learn about mushroom, plate, brain and staghorn corals before learning that, with 1500 varieties of fish, we are unlikely to see them all.
As we approach the reef I remember, with a degree of trepidation, the one and only time I snorkelled. I was 52 years old when I holidayed in Rarotonga, but that was 10 years ago. I floated in about a metre of water just 15-20m from the shore. I emerged from the sea on my knees and came to rest on the sandy shoreline like a stranded, exhausted and near-death beached whale. Never again, I had thought to myself.
Arriving at Agincourt Reef, big sister and I are soon to part ways. She's heading skywards in a helicopter and I'm off to collect flippers, mask, snorkel and a lycra suit to transform me into a black seal. Thankfully I'm told that I look nothing like anything big fish like to eat for fun.
Following John and his handful of novices, we descend the metal steps into the water and follow instructions. Testing my mask for the first time, I pop my head into the clear blue waters and come up in amazement. Fish! Heaps of fish - around my ankles, in front of me, absolutely everywhere.
I launch myself into the sea, armed with my tubular floaty device, and realise that the coral bed is many metres below and I'm out of my depth. But the wonder and beauty of the reef below propels me along as we follow John. Occasionally he dives down to retrieve an animal that we are able to touch. Some sort of sea slug is first, and then the bluest of starfish that one could ever hope to see. He dives down again to replace the specimen in the exact same place from where he retrieved it.
We flipper on. There's no sign of sharks but we all know the signal if we spot one: place one hand on top of your head and point it skywards. If it's a big bugger, use two hands!
As I emerge from the sea after nearly 40 minutes afloat, big sister is there to meet me. "It was unbelievable up there," she says. "You could see everything."
Over a scrummy salad and seafood lunch we compare stories. Sister hadn't experienced close encounters of the fish kind but was stunned by what she saw from the air.
"I'm mostly into educating people about the reef," John tells me on our return trip to Port Douglas. "I tell them about the fish and the corals and how they interrelate with each other. I'm also teaching people to appreciate what's here and pass it on to future generations."
Offering three sites at Agincourt, QuickSilver is able to introduce snorkellers to migratory species that visit the reef such as whale sharks.
I thank John for the unforgettable adventure of a lifetime.
Sister and I are exhausted. We sleep on the transfer coach back to Cairns, where we spend the evening with cousin Sally and her hubby, Terry.
"How was your day?" Sally asks the two pensioners. "Bloody marvellous," we reply, and ask what's for dinner. "Fish," she laughs.