By Sarah Ang

In the old pictures I've seen of the ocean, its colours are sharp and vivid. There is the golden carpet of sand, the brown jagged rocks, the white crests of foam, and the gleaming expanse of blue itself, stretching out to meet the horizon.

These are only pictures, of course. They might have been taken only a few decades ago, but they are remnants of the past nonetheless. The ocean I know is murky, difficult to penetrate. You can hardly swim any distance without encountering floating debris from abandoned ships, or the odd plastic waste from landfills. If you're not used to it, you can barely see in front of you. But years of swimming in these waters have accustomed my eyes to the dim light.

Still, even in its grey, clouded state, the ocean is comforting. It's all I've ever known, living as we do on its fringes, with tide pools literally on our doorstep. It beckons, it draws you under its spell. Now, however, most people keep away from the ocean. The small community we had in this town has largely moved inland, to the cities, and the beaches are desolate. There's certainly no one around today as I step into the water, slipping under the waves with practiced ease.

It's easy to forget things, in the ocean. To let the water sweep over you and erase your memories. Sometimes I forget that I'm human. There's just something about water that calls you to meld seamlessly with it. To lose your sense of self, becoming one with the waves.

"Cultures all over the world have been entranced by the sea," my mother used to say. "Look at the countless tales of sirens enticing sailors off their ships with their song; of mermaids luring fishermen to their watery lairs. Look at the legends of sea monsters across countries, from the Kraken in Norway, to Scylla and Charybdis in Greece, to the Umibozu in Japan. From the beginning of time the ocean has been revered as a deity in its own right." Even now her words still resound in my ears. "The ocean has power. It can choose to reward, but also to punish."

My mother was a marine biologist. Growing up, our house always smelled faintly of the sea. Our living room was plastered with tide charts; maps detailing whale sightings; infographics enumerating various species of fish. Practically every corner of our house contained bowls with specimens of some dried-up kelp, sea grass or coral that she was studying. My sister and I spent our afternoons drawing sea monsters while she drafted sketches beside us, or typed strings of numbers into spreadsheets on her laptop.

Other parents treated their children with weekend trips to the park or city; my mother took us out to sea in her dinghy, where she would make every effort to expand our education by showing us the true wonders of the ocean. Needless to say, her vision was far more acute than ours, and she was always the first to spot any creature. "Nurse shark," she would point out when a shadow passed under our boat, and we would clamber over each other to see more, almost capsizing the vessel in our excitement. "Parrot-fish school," when a flash of green and pink caught our attention. And our favourite, "Humpback whale family," identified by black mounds breaking the surface, and spouts of water being expelled in the distance.

Every morning, she would get up before dawn, slip into her yellow wellingtons, and inspect the tide pools. She would come back once the sun had risen, bearing wonderful things in her arms to show my sister and I – rosy-hued shells; baby hermit crabs; spiny starfish. Bleary-eyed, we would stumble out to meet her, eager to inspect her gifts, to hear her regale us with stories about how they were found. I like to remember her this way: larger than life, her figure framed by the rising sun. Coming back to us, not leaving.

Even now, I try to preserve these moments in my mind, but they are fraying at the edges, trickling like droplets away from my grasp. I'm scared one day I'll forget the exact shade of her hair, fanned out in the water as she paddled on her back, playfully splashing at us. The pattern of her brow furrowing while deep in thought about some new underwater discovery. The way her eyes danced when she laughed.

These memories are all I have left. Soon even they will dissolve away – and where will that leave me?

Although, I suppose that's not entirely true. For now, at least, I do have my sister. I say for now, because with each passing day, this once unshakeable fact seems more and more uncertain.

My sister is sick from a disease that has no cure. It took the world by surprise, emerging seemingly from nowhere. One second, everything was normal, and the next, people were falling sick left, right and centre. The symptoms were harmless enough at first – just a cough, runny nose, headache. It seemed to be practically indistinguishable from the flu. But what started off as a common cold soon became more deadly. Coughs turned more serious, and those afflicted began to have trouble breathing, began to feel weak and dizzy. The lucky ones returned to normal after a few weeks. Some, like my sister, lost all feeling in their legs and became permanently bedridden. Others simply succumbed.

When the disease first broke out, it drove governments around the world crazy. Flights were banned. Schools were closed. The number of cases skyrocketed, and so many people were getting sent to hospitals that there were beds pushed out in the corridors, then on the streets. Then people were turned away, told to stay at home to recover, to hope that they were one of the lucky ones, because there simply wasn't capacity to save them if they weren't.

The thing about this disease, though, is that nothing was clear about it. There were rumours going around that it came from wild animals at the heart of the Amazon, traded on the black market. Or that it started from toxic chemicals in the ocean – which would explain why so many in our small community were afflicted. To this day, they aren't sure of the cause. They aren't even sure how it spreads, or why some people are affected, and others aren't. Some people in close proximity to the infected didn't develop it, but there was nothing observable differentiating these people from the rest. Nothing in their genomes that scientists could pick up on, either.

With so many people across the world falling sick, governments ordered their citizens to stay at home. The seaside village where we lived beside the sea, usually bustling with tourists who came to see the whales, became a ghost town. Many moved out while they still could, seeking family in the city, trying to escape the illness that had so many in our village in thrall. And so the world became divided into two – the healthy and the sick. My mother and I on one side of the chasm, my sister on the other. Fighting desperately to bring her over.

Until my mother left me to continue the fight alone.

The sun hangs low in the sky when I emerge from the water's edge. I pad back into the house, trying to make as little noise as possible. My sister is in our shared room – asleep, judging by the slow rising and falling of her chest. Every breath is a battle in a war she cannot win. I pause by the door, assessing her condition. Curled up like a shell, her body looks even frailer. Her breathing seems slightly easier, though, and at least she isn't coughing. Perhaps the medication is working, although it's too early to tell.

My sister stirs, eyes fluttering open. A faint smile spreads across her lips when she sees me.

"Hi, Pearl," she whispers.

I place a hand on her forehead. "No fever? How are you feeling today?"

"Better," she lies. Always the optimist. Her hair lies in a limp, knotted mass above her head, and I smooth through the tangles.

"Have our groceries come this week?"

I pause. "No, but I'm sure they'll be here soon."

I don't tell her that the deliveries stopped two weeks ago, and I don't expect them to resume anytime soon. After our mother left, as two minors living on our own, we had regular visits from concerned neighbours and social welfare officials who made sure we were okay. Then the neighbours left, so it was down to the weekly visit by a frazzled official who dropped off supplies for us, which morphed into a haggard deliveryman who just knocked once and left the food outside the door, and now that appears to be a thing of the past too. I don't blame them – when countries collapse, their welfare systems are usually the first to go. But I am concerned about how we will obtain food from now on.

She frowns. "Okay. Want to read with me?" The books Robinson Crusoe, Twenty Thousand Leagues Under the Sea and Whale Rider lie untouched by her bedside. Before my mother left, she used to read to my sister, predictably books with an aquatic theme. I was far too old to be read to, but I would join in by making sound effects for the ocean, and mimicking dramatic music at certain key moments, much to my sister's delight.

"Maybe later. You should rest," I tell her.

"How was the haul today?" she queries weakly.

"Not that great, but it'll do," I reply.  I step out of the room, and for a moment, my vision blurs.

Perhaps I should explain further. The haul my sister was talking about doesn't refer to fish, in case you were wondering. She was talking about seaweed. Which also happens to be her only chance of survival.

Part of my mother's research found that a particular type of seaweed, found in our waters, was resistant to certain pathogens. When the new disease emerged, she injected it into seaweed cells, and found that the disease simply had no effect. This seemed like a promising breakthrough at first, but there were a lot of complications getting it to human trials – the hospital wouldn't allow their sick patients to undergo tests. Yet my mother was determined to press on, for my sister's sake. So she struck an arrangement with a group of willing doctors and researchers – she would provide them with seaweed for their work on developing a cure. In exchange, they would give us medication for my sister.

Even after my mother disappeared, I honoured this agreement. I drop off bags of the seaweed in a designated locker outside the research facility, collect the medicine in its place. Every morning, I go to the ocean and gather seaweed. When I return, I clean it meticulously, get rid of the salt and detritus clinging to it, pack it carefully away. Then I prepare food for my sister, give her the medicine, lay out her clothes, shower her while she perches on a stool, trying to exercise the parts of her body that haven't been paralysed yet. Sometimes, I read to her, try to keep her mind from atrophying too. I haven't attended school, either physically or online  – all classes moved online once the disease broke out – since my mother disappeared. It was too difficult to concentrate on my studies and take care of my sister simultaneously, and the authorities had too much on their plate, with the spread of the disease, to check on me. The few friends I had left for the cities with their families, and we soon drifted apart. I cling to my daily routine obstinately – it's the only hope I have of keeping my sister alive. Of keeping us both alive.

My mother named me Pearl after the old pearl divers, or ama, in Japan. Usually women, they would get up before the crack of dawn to dive into the sea and bring back oysters and other shellfish. Armed with no breathing apparatus except the strength of their lungs, and traditionally clad only in a white loincloth, they could dive for up to four hours at a time. The crown jewel of their pursuits, though, was finding a pearl in an oyster. Such a find would ensure their families were fed for weeks.

Pearls are fascinating things. When an irritant intrudes inside the oyster, the oyster coats it with countless layers of nacre, more commonly known as mother-of-pearl. As years pass, a glistening pearl is formed.

I think about this a lot. How an insignificant particle could transform into something so prized, after thousands upon thousands of layers. Refined by adversity, purified through pain. Of course, no one asked the oyster if it would like to have its tender inner layers violated. Or how it felt knowing its pain was insignificant, a sacrifice for the greater good. But I digress. Who thinks about the feelings of shellfish?

Like the ama, I rise before dawn to enter the ocean. The currents are weaker then, and it's less likely that I will be pulled out to sea. Once again, I slide under the waves, let the water envelop me. Kick once, twice, propelling myself away.

The seaweed in question isn't located far from the shore. There's a cluster that grows on a rocky ledge at the edge of the reef.  As I approach, their leafy fronds undulate, dancing to the rhythm of the sea. I grab the knife I brought, begin severing them at their roots.

My mother taught us how to swim, of course. How to streamline your body so you slice through the water effortlessly. How to kick with just the right amount of force. And later on, how to dive like the ama, needing nothing but the air in our lungs. We would dive together, plunging into the ocean's depths while my sister kept a watchful eye above. Down, down, feeling the caress of water against skin, seeing the colour of the ocean change as the sun receded further and further away. Past around fifteen metres, buoyancy reverses – the pressure underwater changes, and instead of being pushed to the surface, the diver is pulled down. The ocean stops resisting the intrusion, welcomes us into her embrace.

My mother would point out strange and wonderful things on these dives – hedges of translucent sea anemones, schools of minnows which darted around our feet, brilliantly coloured coral rising from the sea bed. Even in its polluted state, the ocean was still beautiful.

What I liked most of all, though, was the feeling of weightlessness. The ocean folding us into her womb, defying the laws of gravity. My mother, opposite me, mirroring each stroke as we pressed deeper. Then, finally, the ascent, as we burst back to the surface to see the anxiety on my sister's face melt away. Lying on our backs, the three of us would paddle in lazy circles around each other, laughing at some joke my sister was telling. This is the one image I most wish I could freeze, preserve against the erosion of time. Our laughter, pealing like siren song, echoing against the waves.

I rip one of the seaweed fronds away from its base too furiously, and it slips from my grasp, spiraling into the depths below. My eyes sting, and I try to control myself from shaking.

The day my mother left was like any other. It was still dark when I heard her step into her wellingtons, getting ready for her usual dive to collect seaweed. For some reason, that day I stirred from slumber, opened my eyes. "Don't go," I murmured, still in the grip of sleep. Perhaps some sixth sense in me knew what she did not, could not. That the recent storm had made the tides much stronger, impossible to combat. That, ever defiant, she would try anyway. My mother smiled, making a soothing motion with her hands. "Go back to sleep. I'll be back soon."

She never returned. A search party was sent out for her body two days later, but they returned empty-handed. A part of me was glad. In my mind's eye I could still see her riding the crests of the waves, exultant.

When I return to our house, there's a strange car parked outside. As I walk up to the front door, a bespectacled man emerges from the car, followed by a younger woman in a white coat. "Pearl?" The man queries, striding towards me.

"I'm from the Omelas research facility. I'm sure you're familiar with it?' He smiles, but there is no warmth.

"Why did you come here?" I respond, my skin prickling with apprehension.

He hesitates just a fraction. "Let's go inside."

I lead them into our house, watch them fidget as their eyes roam their surroundings, as they try to find their words.

Finally the man speaks. "Are you aware of the arrangement we had with your mother?"

"Yes. I've been placing the seaweed in the designated area, and taking the medication placed there for months now. Is there an issue?"

The woman bites her lip, leans forward.

"Do you know how your mother passed away, Pearl?"

A lump forms in the back of my throat. "She went diving for seaweed one day, and the current took her," I state blankly.

Now the woman is shaking her head, gently but firmly. "Pearl… your mother didn't go to the ocean that day. She came to our research facility. She had been coming to our research facility for months, as one of our test subjects. You see, we were making considerable progress with the cure, and your mother volunteered to have us carry out trials on her. When we did, we found something startling – your mother had contracted the disease as well, but it had no effect on her. We think she developed immunity somehow."

My body is trembling violently; I make no attempt to conceal it. "Is my mother still alive?"

They exchange glances. "Your mother gave her life to the cause, Pearl. One of the trials was… unsuccessful, and we couldn't save her," the woman murmurs.

The room spins, and I press my head into my hands. So, everything I knew about my mother's death is a lie. She didn't go to the sea that day. She didn't die in her element, in the ocean she loved; she died in a clinical room with white walls, fighting to breathe. And me – how was I so blind to what was going on? How could she not have told me?

The man chimes in. "Your mother gave us your DNA samples, and you display even higher levels of immunity to the disease. Based on the levels of the virus present in your blood, you should be comatose, and yet you're…" he breaks off, gestures at me. "Completely fine."

"We believe we're on the verge of a breakthrough, Pearl. But we need your help," the woman pronounces.

"So you killed my mother by experimenting on her. And you want to kill me too?" I retort.

The man shifts in his seat. "We want to be completely transparent with you. There are always… uncertainties in such research. We'll take all necessary precautions, of course. But you have to understand that, as with every experiment, there will be at times be failures, as much as we hope otherwise. This is a trade-off we have to make, given the unknowns about the disease, and the desperate need for a cure. If we succeed, we will save countless lives, but along the way, casualties may be unpreventable."

"What's in it for me? Why should I help you, knowing I could die in the process?"

"Your participation could lead to a cure for the world. You would be doing mankind a great service," he blusters.

The woman interrupts him. "Perhaps more importantly to you, Pearl, we propose a new arrangement for your sister."

I can feel my body tensing. "My sister?"

"If you choose to come with us for testing, she'll be housed in one of our recovery homes, and we'll take good care of her. She'll receive medication daily, and she'll have other residents for company." The woman pauses. "And when we succeed in producing the cure, your sister will be one of the first to receive it."

I've read about these recovery homes; they're notoriously hard to secure a place in, but renowned for their gold standard of health care. It's a bargain, then, similar to what my mother must have struck with them. A life for a life.

"We can't be the only ones who have developed immunity. Why are you choosing me?"

"It's rarer than you might think, actually. We suspect it has something to do with interaction with the ocean. You're not the only one left, but…" she hesitates, and I understand. It's much easier to take someone with only an invalid sister and perform tests on them. No guardian to protect them, to protest the ridiculousness of it all.

Something shifts in the woman's face, and for a moment she seems younger, more vulnerable. Her breath catches. "I'm a mother, Pearl. My daughter is sick as well." I stare into her eyes, and I see this woman cupping her limp daughter's tiny hand in hers, tears streaming down her face. I imagine her bending down to kiss her daughter's forehead, vowing to do everything she can to save her daughter's life.

"Give me a while to think about it," I say.

The man stands up. "We'll come back in a day."

A few weeks after my mother disappeared, I found myself besieged by strange visions. At night, I stared up at the ceiling, too afraid to allow myself to dream. When the inexorable pull of sleep finally won, I dreamt of myself swimming out at sea, but further than I had ever been before. This time, I didn't return. I saw myself landing on a distant island, bedraggled, exhausted. I saw myself taken in by small, bird-like women, wearing only white loincloths, but with smiles as dazzling as the sun. Then I saw myself, with no trace of fatigue, emerging from their huts, laughing with them. Plunging with them into the sea, as if I'd done it all my life. Emerging not with handfuls of seaweed, but oysters, brimming with pearls.

After these visions, I went into the ocean, remaining there for a longer time, treading water, trying to forget. Trying to get rid of the weight pressing on my shoulders, pushing me under. On multiple occasions, I tried to dive further than I ever had before, the pressure ringing in my ears, blotting out my eyesight; the pain mounting until it was almost unbearable. Each time, my reflexes kicked in, and I hurtled back to the surface, gasping for air.

On one occasion I've tried my hardest to erase from memory, I tiptoed into my sister's room, stood there motionless, just gazing at her. A thought flashed across my mind – how easy it would be to lay a pillow across her face, muffle her breathing. Like snuffing out a candle. I recall clutching the pillow to my chest, so forcefully I could hear my own heartbeat. Knuckles clenched, poised for action. Then she shifted, murmured while still asleep. "Pearl. Pearl."

I barely made it to the bathroom before throwing up all over the floor.

I relive these memories while watching the tide, perched on a rock at the edge of the ocean. My thoughts are whirling around in a frenzy. Like minnows chased by a shark, my mother would have said. For as long as I can remember, my life has been here, by the ocean, with my mother and my sister. When my mother disappeared, I knew I had to assume her responsibilities, had to be both mother and sister. I've never considered any other option.

Once again, I slip into the ocean, let the water calm me. I swim slowly but resolutely forward. How easy it would be to fulfil my fantasy, I think. To swim far, far, away and never return. I could find a distant island somewhere, forage for food like the ama. Leave this life behind. Begin anew, alone.

I am farther out than I've ever been before when I hear a familiar sound, and see a black shape rising beneath me. It's a humpback whale – no – three humpback whales. A mother and her calf, and an older juvenile whale. They surround me, vocalizing gently. Humpback whales are part of matriarchal societies, and the calf usually stays with its mother for about a year until weaned, I hear my mother say. An older juvenile is an odd sight at this time of the year, hanging around the mother and new calf. I look at the humpback whales, and I see, once again, the dinghy floating in the middle of the ocean, three figures inside, pointing excitedly at the whales. I see the flash of their grins, hear their laughter pealing.

I think of my mother, taking her last breaths in an unfamiliar room. How she must have known, all along, what her decision would have entailed. Working tirelessly to harvest the seaweed, even as she journeyed to the research facility alone. Hiding her growing fatigue from the barrage of tests behind a ready smile, in an effort to spare us from the truth.

The juvenile inches closer, and I look into its eye, as large as a baseball. In it I see endless possibilities, dancing just within reach. For the first time, I also see, with perfect clarity, the only one I can choose.

I swim with the humpback whales for what seems like an eternity. When I feel my limbs growing weary, the whales escort me back to shore, humming in unison. I sense their presence, back in the ocean, as I clamber across the rocks.

Before dawn breaks the next morning, I climb out of bed, take one last look at my sister's face. She stirs from slumber, mumbles my name. "Pearl?" I smooth her hair.

"Want me to tell you that story?" I ask.

I don't pick up any of the books by her bedside, though. Instead, I tell her about a family of female pearl divers. Who live on a distant island in the sea, and spend their days plunging into the ocean, foraging for food and seeking oysters. I tell her about how their livelihood is threatened by pirates, who deplete the ocean of its stocks and dredge up all the oysters. About how the pearl divers rally together to stop them, chase them away from their island.

My sister yawns, indicating I'm putting her to sleep. "I'm going out into the ocean, okay?" I whisper.

"Stay safe," she murmurs.

"I will," I reassure her, and turn away quickly, blinking furiously.

The car is waiting for me outside. As I get into the back seat, I look at the ocean. The waves are unusually violent today, rising in white crests, crashing on to the rocks. In the distance, I think I see the whales, raising their flippers in salutation.

I focus my attention on the waves, note the constancy of their motion. How the tide may go out, but always comes back in. How the waves always return to the shore.

As we drive away, the sun rises, a gleaming pearl ascending. Casting shadows on the sea's endless expanse.

_____