It’s a trickier mission than it sounds. According to The Ocean Cleanup project, the non-profit that designed and launched The Ocean Cleanup System, there are currently more than five trillion pieces of plastic in the ocean, and 1.8 trillion in the Great Pacific Garbage Patch alone. It’s only one of five areas where this plastic converges. Here’s what you need to know.

What is a garbage patch?

Garbage patches form in five areas in the ocean called subtropical gyres, which are systems of rotating currents that circulate around a single center point. When plastics get caught in one of the gyres, they can’t escape on their own. As more and more waste gets trapped in the currents, it accumulates and becomes more difficult to remove, dangerous to wildlife, and more costly to the economy—in 2014 the U.N. estimated that plastic waste had a financial cost of $13 billion per year in terms of its impact on marine life, tourism, fisheries, and businesses.

Chloé Dubois

How big is the garbage patch?

It’s often reported that the Great Pacific Garbage Patch is twice the size of Texas, but in 2013 the National Oceanic and Atmospheric Administration (NOAA) pointed out that there are no scientifically sound estimates for the size of the ocean’s garbage patches. That’s because they’re not quite the “floating landfills” we often conjure when we try to picture them. As the Pacific Islands Regional Coordinator of the NOAA Marine Debris Program put it, it’s better to think of the garbage patches as “flecks of pepper floating throughout a bowl of soup, rather than a skim of fat that accumulates (or sits) on the surface.”

While the size can’t be measured, the concentration can, and The Ocean Cleanup project estimates that the densest areas of the Great Pacific Garbage Patch could contain up to 200 kilograms of plastic per square kilometer by 2030 if nothing is done.

How does it work?

According to The Ocean Cleanup project, cleaning up the oceans using the current method of sea vessels and nets would take thousands of years and cost tens of billions of dollars. By contrast, their internal estimates indicate that a full roll-out of 60 Ocean Cleanup Systems could clean 50% of the Great Pacific Garbage Patch within five years. A global deployment of their systems, combined with waste reduction at the source, could remove 90% of the plastic in the ocean by 2040.

The Ocean Cleanup Systems consist of a 600-meter long “floater” that has a 3-meter (about 10 foot) “skirt” hanging from it. The design accounts for the fact that most waste plastic in the ocean sits just below the surface. As ocean currents and winds move the system through the ocean, it collects trash without allowing it to escape over the top of the barrier or out from underneath. The system only works because it moves faster than the plastic in the ocean because it is pushed by currents, waves, and wind, whereas plastic is only pushed by currents. That allows the system to “catch up” with the plastic and collect it, rather than moving at the same rate. The plan is that periodically, vessels will come to collect the debris captured by the systems and take it back to land to be recycled.

The critics

Not everyone is convinced that The Ocean Cleanup System is the best approach to removing plastic from the ocean. Miriam Goldstein, who has a Ph.D. in biological oceanography and is now the director of ocean policy at the Center for American Progress, told CNN that she was concerned about the device creating its own environment and disrupting the ecosystem by collecting plankton at the surface of the ocean along with trash. Instead, she advocated methods that collect plastics at the source and prevent them from getting into the ocean in the first place. For instance, a trash wheel operating in Baltimore’s Inner Harbor has removed nearly 2 million pounds of waste in four years.