Our minibus barrels towards Botany Bay with our instructor, former Royal Australian Navy diver Robert Ridge, behind the wheel. In the back are two British lads, flashing enough gold and tattoos to rival the markings of a tropical fish. As we near Bare Island, they chat to us about the mother country and the meaning of the word 'pukka'.
Dubbed 'bare' by Captain James Cook, the island was once used as a garrison. More recently, it served as a shooting location in Mission: Impossible II. Ridge says that, well within the city limits and not far from the airport, the island is one of Sydney's top five dive sites.
Before exploring the depths, we're handed a form that asks, among other things, whether we're pregnant. Then it's time for a briefing on a bench beside an empty snake-show pit. It is interrupted by a stranger who looks like a bandit from Mad Max. He tells Ridge to make sure we 'blow-ins' don't cause an obstruction, adding: 'Captain Cook was the first blow-in and look what happened to the Aborigines!'
Ridge introduces some drills and teaches us scuba's simple sign language. Next, we strip and squeeze into our wetsuits, stashing our belongings in the minibus safe.
My tank and wetsuit fill me with confidence, but it disappears as I step into the chilly Pacific for drills. The 'partial mask flood and clear' exercise, which for some reason makes me think of trench warfare, requires the diver to submerge, prise the top of their mask open a crack then snort the water that leaks in back out through the bottom.
As Ridge demonstrates, my nervous brain seizes up. When my turn comes to perform the manoeuvre, which the British boys manage easily, I gulp water and gag, tasting a trace of vomit. Only after several further attempts do I do it to Ridge's satisfaction.
Before we go under, Ridge teaches us how to control our breathing. Like driving, scuba is all about keeping your cool and not making mistakes.