Four of us went down that day: my old friend Lucia and her husband, Will, my ambivalent self, and a man called Mick, an ex-opal miner with a boozy squint who seemed to take an instant dislike to me. I’d noted it over pre-dawn introductions at the marina and the feeling was instantly mutual. That’s the trouble with misanthropes, I thought: they have a knack for recruiting the rest of us.

It’s not ideal being stuck with a prickly dive buddy – the ocean itself is hostile enough – but Lucia and Will are annoyingly inseparable, so we had no choice but to form two pairs. Anyway, I’d invited myself along on this trip, saying it was time I got back out there. ‘You sure you’re ready?’ Lucia had asked. ‘Completely,’ I’d replied, my tone bright. ‘I’m back amongst the living.’

Our skipper stayed topside with his deckhand cum cook, a young Spanish guy who’d been mooching around all morning with his shirt off. We’d all pretended not to notice, but when Lucia caught my eye we hid conspiratorial smiles – two ageing dames acknowledging a surface loveliness that was now lost to us. We asked the young guy to man the camera.

As we crashed through the looking-glass and began to sink, I repeated the mantra to myself: slow and steady, keep breathing, trust your gear. That morning over coffee in the cramped galley, we’d scrutinised the blurry maps, vague blueprints of the wreck’s remains, but they couldn’t tell us much. Only that her century-old bones lay deep and widely scattered, playthings for the rough seas and strong ocean currents that swept this area.

The Steadfast had sunk more than a century ago, smashed on the dark rocks of a tiny offshore island so steep and wave-beaten that it held almost no soil or plant life. Thick fog, no visibility, an unmapped rock ... the exact verdict was a guess, because all on board were lost.

But there was one certainty: along with sundry unremarkable cargo, the steamship was also carrying a consignment of gold and silver coins, fresh from the National Mint. Most of the coins were recovered during a major salvage operation in the 1960s, but some remained unfound. The wreck’s ownership is disputed, and few divers are willing to brave the fierce currents that clash out there beyond the headland, roiling and entwining in a turbulent slipstream.

Will’s take on it was that we weren’t here to steal, but anything we found could be considered a fair souvenir. ‘Finders keepers’, as he put it. None of us was short of funds, but lost treasure has its own peculiar appeal: an aura of chance or luck, of being rescued from the depths. Or it may just be that childish delight in treasure hunts; perhaps it never fades.

Lucia and Will swam down first, holding the anchor rope as they descended into the gloom. Their exhaled breath rose away on a diagonal slant, pearls of air strung sideways by the current. Mick, being more experienced, led me down after them, not glancing back to check on me. The water was colder than I’d expected. As I followed him down the rope, I felt the current pull and nudge at me, like some huge prehistoric creature nosing at a floating speck of flotsam. A dart of fear shot through me, and I felt the water pressing in from every side, countless cold tonnes of it, alien and indifferent; I felt the urge to fight for air that was already flowing safely through my lungs. But I kicked on through it, following Mick down the anchor-line, counting off the depth until the feeling passed: thirty feet, forty feet, fifty and on down.

The light faded as we sank. The Steadfast lay strewn across an ocean floor pockmarked with deep cracks and caverns. Her remains were 120 feet down at the deepest point; as we all knew, that translates to fifteen minutes of bottom time, no longer. We passed a good-sized grouper, a curious specimen who fixed me with a bulging eye and mouthed the water amiably, as if making conversation.

Eighty feet down Mick finally turned to check I was behind him. Some dive buddy, I thought, as I returned his OK signal. He peered at his compass and pointed up-current – we’d agreed to swim against it to counter the drag, enter the wreck site from its northern edge – and I nodded. Below in the gloom I could see the toylike figures of Lucia and Will heading for a flat section of the ocean floor, just beyond the area Mick and I had opted to explore. I could just make out our destination: an uneven moonscape riven with hollows and cracks. Clumps of wreckage must have lodged down there, nestled into rocky fissures or small caves.

Once we reached the hundred-foot mark we struck out into the blind push of the current, heading for the bottom. Deep water leaches out colour, so the ocean floor was a listless palette of browns, blacks, and greys. We reached the rock-strewn depths and clung there a moment to check our gauges. On every side rose mini-mountains, some hollow and crumbling, others split by dark crevasses that led down into blackness. Here and there, wedged between the mounds, lay a scatter of recognisable debris: a rusted steel girder, a bluestone ballast block, a length of pipe, all encrusted with waving tendrils of sea life.

We swam around, scouting, until I found a hole the size of a small car and gestured Mick over. As we shone our torches down into its mouth, a riot of colours sprang out from where the beams hit the far wall: sulphur-yellow, cobalt blue, delicate pinks and raw reds, a pile of rocky shelves teeming with life. The cavern was about thirty-five feet across, its sandy floor twenty feet below. We checked our watches and our air, exchanged the OK signal and swam into the hole. Twelve minutes, I remember thinking.

Underwater caves have always frightened me, but this one suggested shelter rather than suffocation. It was dome-shaped, and the far side opened out into a majestic archway, yawning like a cathedral entrance. Milky light spilled down from above, silhouetting the near-perfect arch, a marvel of undersea architecture. A school of fish shimmered just beyond it, a silvery ball of darting motes, and my torch beam lit up purple sponges, tangerine corals, and strands of swaying plant-life, arranged around the walls in technicolour. I remember feeling a strange mix of calm and excitement. The current was almost imperceptible in there.

Mick pointed to the sandy floor, which was scattered with flotsam, fragments of what might be wreckage. I chose my own search area nearby, a rocky shelf that jutted out from the wall. Up close, the cavern’s surface was a busy micro-world: chubby starfish clung to the rock face, a row of crayfish feelers waggled from a crevice, and a grizzled moray eel gaped out at me in open-mouthed disdain. At the edge of my torch beam hovered a rotating cast of curious fish: blue, emerald, inky black with red flecks.

I checked my watch and decompression meter: ten minutes left. Focus, I reminded myself, You can see fish anywhere. The ledge surface was scored with cracks, some home to tiny translucent crabs and feathery anemones, others silted up with sand and miniature shells. Right off I spotted a white triangle wedged into one crack, a shape not made by nature, and pulled it free: a shard of broken crockery, patterned with a tracery of blue flowers. A quick thrill shot through me – my first find. I tucked it inside the sleeve of my wetsuit for safekeeping. Excited now, I waved my hand over the cracks to dislodge the loose sand, sending it whirling upward.

Then a new shape: at first it looked like the curved spine of some sea creature, hiding in a crack. It was wedged deep, settled in with sand and grit, and I had to remove my glove to get a grip on its slim edge and wriggle it free. It came loose slowly, like a reluctant tooth. Only when I placed it flat in my bare palm, wiped its surface clean, did I realise what I held: there in my torch beam winked a gold disc, thumbnail-sized and unmistakeable. A half-sovereign with an intricate image stamped on its face: a helmeted man astride a rearing horse, plunging his sword into some coiled creature writhing on the ground. Saint George, slaying the dragon. And below, a date stamped in hair-thin numbers: 1902.

How long did I examine that coin, turning it over and over in the torchlight, engrossed? I have no idea, but I remember feeling a mild exhilaration, a rare sense of delight. On the flipside was the profile of a bearded man, the king of the day – one of the Edwards, I guessed – encircled by more minute text, too small to read clearly, perhaps abbreviated Latin. I fixated on the design, his features rendered in miniature: the delicate whorls of his ear, the hooded eyelid beautifully cast. So small, so perfect. Stash it somewhere safe, I thought, but part of me was reluctant to let go of it.

That’s when I became aware of Mick hovering beside me, his torch beam wobbling over the shelf and lighting on my open palm. He peered in close, shone his torch full beam onto the coin, and I fought the urge to hide it, clamp my hand into a fist. He drew back in pantomimed delight; then patted my back, just softly, raised his arms into a victory sign. I could feel his excitement, see his squinty eyes through the glass of his mask, but I just wanted him to go away. This rocky shelf was my find, my treasure trove, and I wanted to keep searching: surely there was more? But still he hovered, as if waiting for me to move aside and let him have his turn. And then politely, almost apologetically, he tapped his watch.

My irritation quickly vanished. What did it matter? I felt magnanimous, almost euphoric: I had my find, this one perfect treasure, and it was enough. Mick was free to try his luck. I waved my arm over the shelf, as if inviting him to tuck into a buffet. I held the coin tight, stuffed my loose glove into my belt and pushed off, drifting backward. Mick could help himself, I didn’t care. I didn’t wait to see his reaction, just left him there. Good luck to him, I thought. I’ve got Saint George, and old Edward, and the poor butchered dragon. That’s all I need.

Rule number one is never leave your dive buddy, but the cavern wasn’t big, so I didn’t drift off far. I swam lazily to the far wall, where that graceful arch led out to the open sea. Shining my torch around its edge, I floated there, drinking in the other-worldly colours and shapes of sea life festooning the walls: a baby octopus ambling through a forest of pink coral; a fringed plant waving at me, blue fingers pale as frosted glass; iridescent fish shot with neon streaks, their mouths curved upward in private fishy smiles. I glanced back once at Mick, bent over the shelf, fossicking, then forgot him. The rock face before me was decorated like an outlandish filmset, an alien world conjured up by some mad oceanic wizard, and I could have drunk it in forever.

That’s when I heard it: faint at first, then gradually swelling louder. I drifted toward the sound, turning my head this way and that to catch its cadences as it grew clearer: the slow rise and fall of a piano, in a major key, snatches of a song so beautiful it almost hurt to listen; I half-recognised it. Something about moonlight? Suspended there, looking up at the arch of the cathedral, I felt the sound wash through me like an ocean current, touching every cell – permeating my skin, my blood, my muscles and bones with a swirling lightness.

When I drifted upward a little, the music faded; when I sank back down a few feet, it returned, filling me with a drowsy rapture so lovely that I felt tears spill down my face, warm saltwater trapped inside my mask. For a while I bobbed up and down there, playing with the volume, bringing it in and out of earshot. Then, looking up through the opaline light of the archway, I saw a huge manta ray glide past, like some albatross of the deep, its wings undulating in perfect time with the melody. I swear it waved at me. I felt the urge to laugh, to call out to it. There was a bitter taste in my mouth, and I reached up to tug my mouthpiece free.

Then a hand gripping my arm. Shaking me hard. And there, right beside me, was James. My James, my Jimmy ... I drew him close and cupped his cheek in one hand, but he grabbed my wrist, shook it off. He kept pointing upward, jabbing now, insistent; he looked silly, so serious, with his hair waving around like seaweed and his face distorted by the mask. I felt like giggling. I tried to remove my mouthpiece to tell him about the ray, but he jammed it hard against my teeth and held it there. Hurt, I peered at him through the window of his mask. That’s when I noticed that his eyes were wrong; a stranger’s eyes.

Memory has blanked out most of our ascent, but there was no music as Mick led me out of the cave, up through the hole we’d entered. Then we must have followed the anchor-line upward. Come up no faster than your bubbles rise; pause at certain depths to let your body decompress: the golden rules. But I don’t remember any of that.

What I do recall clearly is sitting on deck, hearing a voice whimpering: ‘Where’s Jimmy, where is he? My coin, my coin ...’ Lucia was stroking my face, making soothing noises, shushing me. ‘That was close,’ I heard Mick say. ‘She was off with the mermaids.’ The skipper was wrapping me in a blanket. ‘What happened?’ said the Spanish guy, and I peered up to see him holding the camera, still filming, its black eye pointed at me. ‘She’s narced,’ the skipper snapped. ‘Turn that bloody thing off and bring her a hot cup of tea, with milk and sugar.’

Nitrogen narcosis, also known by its more poetic name ‘rapture of the depths’, doesn’t hang around: the effects disappear within minutes. It can strike anyone, but more experienced divers learn to read the symptoms early. Old salts like to call it the Martini effect – once you’re sixty-six feet down, every extra thirty-three feet you descend equates to one dry martini on an empty stomach. I knew all this, once my head cleared, but I was shaken by what I’d seen down there: his face, so close we could have kissed, and then that awful moment when he vanished again. And then there was the coin. It was, as they say, no longer on my person.

Lucia helped me dry off and get dressed, propped me on a pile of pillows in her cabin, plied me with blankets, shortbread biscuits, and more tea. I felt foolish and adrift, like a petulant child, and couldn’t shake a sense of loss. I didn’t want to talk about what I’d seen, knew it was a hallucination, and after several attempts Lucia left the subject alone. What I did fixate on was that coin. ‘You must have dropped it,’ said Lucia. ‘I pulled off your wetsuit myself, there was nothing except that bit of pottery digging into your arm. Christ, Hannah – you’re alive. That’s what matters.’ But I could not believe I’d let go of my treasure, let it sink back down to the ocean floor.

She showed me what she and Will had found: two discoloured silver coins, a single tile with a pretty black-and-white rococo pattern, a small glass perfume bottle, almost intact. I held the tile, traced the lines with my thumb. ‘And what did Mick find?’ I asked. ‘Two gold coins,’ said Lucia. ‘Stuck in the cracks, near where you found yours.’ I shot her a glance, and she gazed levelly back at me. I knew I was being childish. ‘Lucky him,’ I said sourly.

‘You’re upset,’ she said. ‘You’re still grieving.’ She moved to hug me, but I stayed rigid, feeling angry but faintly ridiculous, with my plate of biscuits and someone else’s worthless memento in my lap. She persisted, so I briefly returned the hug, then leant back, ending it. ‘That man thinks I’m an idiot,’ I said. ‘Inexperienced. And I could tell straight off he didn’t like me.’ Lucia shook her head. ‘That’s not true,’ she answered. ‘It can happen to anyone, we all know that. Go easy on him, Hannah. He’s a bit grumpy lately, but it’s not personal. It’s been one hell of a messy divorce.’ She convinced me to lie down and rest, and sleep soon overtook me.

When I woke up the porthole was dark and the smell of cooking wafted through the boat. A knock on the wall, and Will poked his head around the curtain. ‘Hungry?’ he grinned. My head was clear now, and I swallowed my embarrassment, gave a bright reply. ‘So long as it’s not fish,’ I said, and followed him into the cramped galley.

Everyone looked up when we came in, except for Mick, who was studiously pouring a round of drinks. The Spanish guy was heaping pasta onto plates, with some kind of ratatouille sauce. I squeezed into the booth seat next to Lucia, glanced around the table. The skipper passed me a tumbler half full of amber liquid. ‘Whiskey sour,’ he winked. ‘Put hairs on your chest.’ Lucia rolled her eyes: ‘Just what every woman needs.’ We laughed, and ate, and everything was normal again.

I sank that whiskey faster than I usually would. Felt my blood level out, the tension in my shoulders fall away. The water out here was choppy, and the boat rose and fell, slapping down hard and following the tug and surge of those duelling currents. When Will spilt sauce all down his front, the skipper offered him a baby’s bib some relative had left behind on a past trip, and Will tied it round his neck with great dignity, pulling a haughty face.

My glass was nearly empty when I caught a gleam amongst the melting ice-cubes. I glanced around, but the others were all talking and laughing, seemingly oblivious. When I fished the coin out and held it up to the light, the table fell quiet. Then Will let out a low whistle. ‘Well, well,’ he said theatrically, ‘What have you got there.’ It wasn’t a question.

I looked at Mick, unsure what to feel. Angry? Patronised? Grateful? ‘What’s this?’ I asked, stalling. He shrugged. ‘It’s yours. You found one, so did I.’ They all stared at me expectantly, like grandparents watching a child unwrap a birthday gift. ‘Finders keepers?’ said Will hopefully, half-raising his glass. Mick grinned at me then, his face creasing up like a cheeky kid, and I smiled back. Held my own glass high. ‘To Saint George and that poor old dragon,’ I said. ‘Gone but not forgotten.’

Later, watching the video at home, I fast-forwarded the bit where I lay gasping on the deck, skipped over the raw distress that no one should have had to witness. But I watched the last scene several times. I’d shot it from the pier in a blustery wind as the boat pulled out from the marina, heading up the coast to drop the others home. The weather had cooled, so the Spanish guy had put his T-shirt on, much to Lucia’s disappointment. The skipper was out of shot, steering, but the others waved goodbye in unison. All except for Mick. As the boat drew away into the distance, he just stood there with one hand aloft, making the OK signal for the camera.

‘Narcosis’ was commended in the 2011  Australian Book Review Elizabeth Jolley Short Story Prize.

 Click here for more information about past winners of the Jolley Prize.