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What Is Ocean Plastic?

How many times did you touch plastic this morning?Everything You Need to Know About Marine Plastic — An Ocean Health Check Through the Third World Ocean Assessment (WOA III)When you picked up your toothbrush, that was once.When you squeezed your shampoo bottle, that was twice.When you twisted open the cap on a milk carton, that was three times.Add a coffee cup lid and a straw, and you probably touched plastic more than ten times just this morning.It feels like nothing out of the ordinary. But when these ordinary days pile up, they begin to change our oceans.Plastic is, without question, a useful material. It is light, cheap, and durable, which means it can be used for a long time. But that very advantage — the fact that it does not easily break down — has become the ocean’s most frightening curse. A single straw we use for five minutes and throw away can remain in the sea for hundreds of years.Five minutes and hundreds of years.It is almost like a brief mistake made by one person leaving a trace that cannot be erased for generations. That enormous gap in time is where today’s story begins.▲ What Is Marine Plastic? Video in preparationSource: Sunhak Peace Prize Official YouTube Channel― 2026 Ocean “Health Check” Results: Very PoorSummary of the United Nations Third World Ocean Assessment (WOA III)―▲ Cover of the Third World Ocean Assessment report published by the United Nations.Source: United Nations / WOA IIIOn World Oceans Day 2026, the United Nations released the Third World Ocean Assessment (WOA III). It is a report in which hundreds of experts from 86 countries conducted an integrated diagnosis of the ocean from environmental, economic, and social perspectives. In other words, it is like “the regular health checkup results for a patient called the ocean.”The problem is that the results are far from good.One of the most alarming findings in this 1,600-page report was plastic. Today, more than 4,000 marine species are known to be affected by plastic. If we compared this to humans, it would be as if nearly half of the global population were suffering at the same time from a single cause.WOA III states that plastic disrupts almost every aspect of marine life — from feeding behavior to immunity, growth, and reproduction.So what condition is the ocean in right now?Let’s break it down one by one. Five Things You Should Know About Marine Plastic1. What we see is only the tip of the icebergPlastic floating on the surface or piled up on beaches accounts for only 3–4% of the total.2. The smaller it gets, the more dangerous it becomesMicroplastics and nanoplastics are difficult to track and remove, but they can enter living organisms most easily.3. Everything is connectedPlastic does not come alone. It accumulates alongside climate change, overfishing, and pollution, placing even greater pressure on the ocean.4. The ocean’s problem is our problemPlastic pollution comes straight back to us through the livelihoods of fishers, the food on our tables, and our health.5. The solution is prevention, not cleanupRather than collecting plastic after it has already been discarded, it is more important to produce and use less from the beginning. ― Visible Plastic Makes Up Only 3–4%Where did the invisible 96% go?―When we think of marine plastic, we usually imagine scenes like these: the massive “garbage patch” floating in the middle of the Pacific Ocean, plastic bottles endlessly washing up on beaches, or a straw harming a sea turtle.But there is an even more shocking fact.The plastic we can see with our eyes accounts for only 3–4% of all plastic in the ocean. In other words, even the images that shocked us were only the tip of the iceberg.So where did the remaining 96% go?Some of it has already sunk into the deep sea. Some has broken into tiny fragments and scattered. Some has spread throughout the ocean in forms that are now extremely difficult to recover.Just because we cannot see it does not mean it has disappeared.It has become harder to deal with precisely because it has become invisible. Every year, an estimated  52.1 million tons of plastic enter the ocean.If we consider one large elephant to weigh about 6 tons, that means we are pouring the equivalent of  8.7 million elephants worth of plastic into the ocean every year. And not just once.Last year, this year, and next year — again and again. There is one more meaningful figure to consider.Humanity has mapped only 27.3% of the seafloor.That means more than 70% of the ocean floor remains, quite literally, unknown territory that has not yet been properly mapped.And in that dark, unseen space, we still do not fully know what is happening to the invisible 96% of plastic — or how it is changing. How Much Do We Really Know About the Ocean? Visible Plastic4% Mapped Seafloor27.3% Unmapped Seafloor72.7% ▲ Visible marine plastic accounts for only 4% of the total, and humanity has mapped just 27.3% of the seafloor.Source: WOA III (2026), UN News (June 2026)― Where Does Plastic Enter the Ocean?Single-use plastics and ghost fishing gear―Where does all this plastic come from before it flows into the ocean?The starting point is closer than we might think.A large share of plastic enters the ocean through rivers and streams.Imagine a single plastic bag discarded in a city.It enters a storm drain.It moves into a stream.It flows into a river.And eventually, it reaches the sea.In that sense, rivers act like conveyor belts carrying plastic from land to the ocean.That is why the statement “I don’t live near the coast, so marine plastic has nothing to do with me” does not hold true.Almost all waterways on Earth eventually meet the ocean.So which plastics are the biggest problem?WOA III points to two main culprits.▲ Single-use plastics — These account for around 40% of global marine litter. Common examples include cups, straws, bags, and packaging materials that are used once and thrown away.▲ Abandoned fishing gear — This accounts for around 15%. Nets and fishing lines that are discarded or lost at sea become “ghost gear,” trapping marine life for a long time.Together, these two categories make up nearly half of the total.So the key point is clear:We need to take another look at the things we use too easily and throw away too quickly. What Is Global Marine Litter Made Of? Single-use Plastics40% Abandoned Fishing Gear15% Others45% ▲ Single-use plastics and abandoned fishing gear together account for nearly half of all marine litter.Source: WOA III (2026)― 24 Trillion Pieces — More Than the StarsThe risks of microplastics and nanoplastics―So what happens to plastic after it sinks and breaks apart?Does it disappear?No.Rather than disappearing completely, plastic becomes smaller and smaller. MicroplasticsMicroplastics are plastic fragments smaller than 5 mm — about the size of a grain of rice or smaller. When plastic breaks down into even smaller pieces, it is called nanoplastic. This is where the problem begins.Plastic does not become less dangerous as it gets smaller.In fact, it becomes harder to find and harder to filter out.According to estimates in WOA III, there are as many as 24.4 trillion microplastic particles in the world’s upper ocean.Considering that the Milky Way is estimated to contain about 100 billion to 400 billion stars, the number of microplastics floating near the ocean surface is, quite literally, greater than the stars. Microplastics in the Ocean Surface vs. Stars in the Milky WayMicroplastics in the ocean surface · 24.4 trillion particles Stars in the Milky Way (estimated) · 100 billion–400 billion ▲ Microplastics in the ocean surface are estimated to outnumber the stars in the Milky Way. The length of the bars is an illustrative expression for relative comparison.Source: WOA III (2026)But what is even more frightening is nanoplastic — particles even smaller than microplastics.WOA III is honest about this uncertainty. It acknowledges that we still do not fully understand the long-term effects of nanoplastics on living organisms.But “we do not know yet” does not mean “it is safe.”It means we have not yet been able to fully measure the scale of the risk.In fact, nanoplastics have already been found in human blood, lungs, and even the placenta.What began as a story about the ocean has now reached inside the human body.So what happens when these tiny particles enter living organisms?WOA III points to the following effects. ① Disruption of the immune systemThe body’s defense system begins to malfunction.② Inflammatory responsesInflammation can occur in different parts of the body.③ Reduced growthLiving organisms may not grow properly.④ Energy imbalanceThe balance of energy needed for survival can be disrupted. ― Plastic Is Ultimately a Climate IssueThe relationship between marine plastic and climate change―The problem does not end there.The ocean is not suffering from plastic alone.Climate change, overfishing, biodiversity loss, and pollution are accumulating all at once, placing enormous pressure on the ocean.In particular, plastic and climate change share the same root.That is because most plastic is made from petroleum.Producing more plastic also means becoming more deeply dependent on fossil fuel-based industries.The problem of plastic accumulating in the oceanand the problem of the ocean growing warmerare not two completely separate issues.They are like two streams of smoke rising from the same chimney.That is why reducing plastic is not only a way to protect the ocean.It is also a way to protect the climate.― The Solution Is Prevention, Not CleanupReducing production and the global plastics treaty―What should we do for the ocean?Beach cleanups and recycling are necessary.But they are not enough.If a bathtub is overflowing, wiping the water off the floor is important.But what should we do first?We must turn off the tap.If recycling and cleanup are like mopping up the water on the floor, reducing production is like turning off the tap. Two Things We Can Do1. At the institutional and international levelThe Intergovernmental Negotiating Committee (INC), led by UNEP, has been discussing a legally binding global plastics treaty. However, countries have not yet reached an agreement on who should reduce how much, and who should bear the cost.Still, 57 international treaties for the ocean are already in operation, including the agreement on fisheries subsidies and the BBNJ Agreement, which protects biodiversity on the high seas.2. At the individual and citizen levelReducing production, expanding reuse, improving product design, and creating alternatives to single-use plastics are all necessary.Individual recycling alone cannot stop the flow of 52.1 million tons of plastic all at once.But one tumbler, one reusable shopping bag, can become a signal that says:“I want a different way.”And that signal can become pressure that moves companies and governments to make different choices. The ocean is connected as one system.Even if one country works hard to clean its beaches, plastic flowing in from somewhere else can ride the currents and wash back again.That is why, when it comes to ocean problems, “as long as we do our part, it will be enough” is not a solution that works.― From Passive Inheritors to Active GuardiansAction for future generations―The theme of this year’s World Oceans Day was this:“Re Imagine: A new relationship with the ocean beyond the world we know.”The United Nations invites us to move from being “passive inheritors” who simply receive the ocean’s generosity, to becoming “guardians” who actively protect the ocean’s future.An inheritor uses what has been passed down.But a guardian thinks about what will remain even after they are gone.The plastic we release into the ocean today will break down into particles smaller than 5 mm and drift through the sea for hundreds of years.In a sense, we are already placing our disposable cups inside the bodies of fish that generations not yet born may one day eat.Before this is an environmental issue, it is an issue of justice between generations.What we can do is not necessarily to become grand heroes.It is to not look away.It is to remember the invisible 96%, to keep listening for news of whether stalled agreements begin moving again, and to keep questioning our dependence on single-use products.One tumbler may not save the ocean.But it can become a signal. “I want a different way.”“Convenience also requires responsibility.” When enough of these signals come together, they become pressure that can move corporate decisions and national commitments.Tomorrow morning, we will still pick up our toothbrushes and twist open cup lids.What needs to change may not be plastic itself, but our attitude — the belief that we can use it so easily and throw it away without a second thought.. . . .The moment that attitude changes, we become not the people who damage the ocean, but the people who protect it.Written by Sharon Choi Director of PlanningSunhak Peace Prize Secretariat  Further ReadingsWhat is the IPCC(Intergovernmental Panel on Climate Change)?What is Great Pacific Garbage Patch?Things we must do for a sustainable ocean References & Sources1. United Nations, Third World Ocean Assessment(WOA III), 20262. UN News, 「Five things you need to know about ocean plastics」, 2026.6