What plastic pollutes the ocean the most? Top sources and who’s really to blame

Every year, over 11 million tons of plastic end up in the ocean. That’s like dumping a garbage truck full of plastic into the sea every minute. But not all plastic is the same. Some types show up in huge amounts on beaches and in ocean gyres, while others vanish quickly or break down in ways we don’t fully understand. So what plastic pollutes the ocean the most? The answer isn’t just about what you throw away-it’s about what companies make, how much they make it, and where it ends up.

Polyethylene is the #1 ocean pollutant

The most common plastic in the ocean is polyethylene. It makes up over 70% of all plastic debris found in marine environments, according to data from the Ocean Conservancy and the United Nations Environment Programme. Polyethylene comes in two main forms: HDPE (high-density polyethylene) and LDPE (low-density polyethylene). You’ve seen both. HDPE is in milk jugs, detergent bottles, and shopping bags. LDPE is in food wrap, sandwich bags, and the thin plastic lining inside coffee cups.

These materials are cheap, flexible, and easy to mass-produce. That’s why they’re everywhere. And that’s why they’re the most common thing washing up on shorelines from Bali to the North Sea. A 2024 study analyzing over 200,000 pieces of plastic collected from 12 coastal regions found that 73% were polyethylene-based. Most of it was single-use packaging-wrappers, bags, caps, and containers.

Who makes the most of this plastic?

The companies producing the most of this pollution aren’t hidden. They’re household names. Three corporations-ExxonMobil, Dow, and SABIC-account for nearly 15% of global virgin plastic production. ExxonMobil alone produces over 1.5 million tons of plastic resin each year, mostly polyethylene. Dow, based in the U.S., produces over 12 million tons annually, with more than half of it being polyethylene for packaging. SABIC, headquartered in Saudi Arabia, is the largest producer in the Middle East and supplies plastic to brands across Europe, Asia, and North America.

These companies don’t sell plastic bags directly. They sell resin pellets-tiny plastic beads-to packaging manufacturers. Those manufacturers turn them into bottles, wrappers, and containers that end up in the hands of brands like Coca-Cola, Nestlé, PepsiCo, and Unilever. The irony? These same brands run global campaigns about recycling and sustainability, while continuing to rely on single-use polyethylene packaging for over 90% of their products.

Why polyethylene dominates ocean pollution

It’s not just that polyethylene is made in huge volumes. It’s also designed to be disposable. Unlike PET bottles, which are often collected for recycling because they’re worth money, polyethylene packaging has almost no resale value. A plastic grocery bag weighs less than 5 grams. Recycling it costs more than making a new one. So most of it gets thrown away after one use.

It doesn’t biodegrade. It photodegrades-breaks into smaller pieces under sunlight. These become microplastics, invisible to the naked eye but deadly to marine life. A 2023 study from the University of Manchester found that 87% of plankton samples from the North Atlantic contained microplastic fragments, almost all of them polyethylene. Fish eat them. Seabirds mistake them for food. Turtles confuse plastic bags for jellyfish.

And because polyethylene floats, it travels. Ocean currents carry it across continents. The Great Pacific Garbage Patch, a swirling mass of debris twice the size of Texas, is 94% polyethylene. It’s not just one place. Similar accumulations exist in the Indian Ocean, the South Atlantic, and the Mediterranean.

Other plastics in the ocean-still a problem, but less common

Polypropylene is the second most common plastic in ocean waste. You’ll find it in bottle caps, straws, and food containers. It’s also lightweight and floats, so it spreads easily. But it only makes up about 12% of ocean plastic-far less than polyethylene.

PET (polyethylene terephthalate) is the plastic used in soda bottles. It’s more often recycled because it has value. Still, millions of bottles leak into the ocean each year. Polystyrene (Styrofoam) is another offender, especially in food packaging. But it’s brittle and breaks apart quickly, so it’s harder to track. And while it’s highly visible on beaches, it doesn’t make up nearly as much of the total mass as polyethylene.

Even though these other plastics are harmful, they don’t come close to the sheer volume of polyethylene. It’s the backbone of disposable culture-and the backbone of ocean pollution.

What’s being done-and why it’s not enough

Many companies claim they’re switching to “recyclable” or “compostable” packaging. But most of these alternatives still rely on polyethylene. A “compostable” bag might look different, but if it’s made from PLA (polylactic acid) blended with polyethylene, it won’t break down in the ocean. It just turns into microplastic faster.

Recycling programs are broken. Less than 9% of all plastic ever made has been recycled. In the U.S., only 5% of plastic bags get recycled. In the UK, it’s 1%. The rest goes to landfills, incinerators, or the environment. Even when collected, much of it is shipped to countries with weak waste systems-like Indonesia or Nigeria-where it often ends up in rivers and eventually the sea.

Voluntary industry pledges? They’ve failed. A 2025 audit by the Corporate Accountability Initiative found that 78% of major plastic producers missed their 2025 plastic reduction targets. None came close to cutting virgin polyethylene production.

What actually works

Real solutions don’t come from better labels or recycling bins. They come from reducing production. Countries like Canada, the EU, and Kenya have banned single-use polyethylene bags outright. Rwanda banned all plastic bags in 2008-and now has some of the cleanest streets in Africa.

Some brands are stepping up. Lush Cosmetics sells shampoo bars wrapped in paper. Loop, a global reuse platform backed by Unilever and PepsiCo, delivers products in durable containers you return. These aren’t perfect, but they cut plastic at the source.

Change starts with pressure. Consumers can’t recycle their way out of this crisis. Only policy and corporate accountability can. The plastic polluting the ocean the most isn’t your fault. It’s the fault of companies that keep making it-by the millions of tons-and calling it sustainable.

What you can do

You don’t need to live a zero-waste life to make a difference. Start by asking: Who made this? What’s it made of? And do I really need it?

• Choose products in glass, metal, or paper instead of plastic.
• Support brands that use refill systems or eliminate packaging entirely.
• Don’t buy bottled water. Carry a reusable bottle.
• Write to companies and ask them to stop using polyethylene packaging.
• Vote for leaders who support plastic production caps, not recycling promises.

The ocean doesn’t care about your recycling bin. It cares about what gets dumped into it. And right now, the biggest dump is polyethylene-from the biggest plastic makers on Earth.