Have you ever been to a garbage landfill? Have you seen cities where the garbage lies on the street without ever being cleaned up? If you have, you know all about the smell and the general unpleasantness. Did you know that the biggest landfill in the world is actually not on land but in the water? Far out in the Pacific Ocean is an area called the Great Pacific Garbage Patch, where plastic and other litter has been floating around and polluting the water. The patch is a major concern for scientists and other people who want to keep the oceans healthy.

The world’s biggest garbage dump is made up of two sections in the Pacific Ocean, one between California and Hawaii and the other off the coast of Japan. The two sections are connected by a current called the Subtropical Convergence Zone and together make up the Great Pacific Garbage Patch. The area where the Garbage Patch is located is called the North Pacific Subtropical Gyre, a section of slowly spinning water. The area is often called an oceanic desert since it has very few plants or animals other than tiny plankton.

Instead of animals, however, the North Pacific Subtropical Gyre has huge amounts of garbage, about 90% of which is plastic. The trouble with plastic is that it never completely disappears but instead photodegrades, breaking into smaller and smaller pieces of plastic called “mermaid tears” or “nurdles.” Garbage can float around in the ocean for years or even decades, but eventually it ends up in one of the garbage patches, often floating just below the surface or sinking down to the ocean floor. Some scientists estimate that the size of the garbage patch could be as big as the state of Texas, although others believe it to be much smaller. However big it is, it’s a cause for concern.

As the pieces of plastic or other garbage float around in the water, they pick up poisons from fertilizers and other substances that wash into the ocean or they join other kinds of garbage floating in the water. Thousands of birds and marine animals, possibly up to a million every year, die from eating or being caught in the ocean’s garbage. Debris that floats in towards the land pollutes beaches along the coasts of countries like Japan and Canada, sometimes even piling up several feet high in some areas.

Where does all of this garbage come from? Some of it comes from people dumping trash from ships, but about 80% of it comes from land. It could be garbage carried by the wind from landfills or from city streets, which eventually makes its way to the ocean. It could come from litter that people drop into in the lakes and rivers before it floats down to the oceans. That’s why some towns have banned plastic grocery bags, which make up a large part of the litter. In some towns and cities, volunteers help to clean up beaches and other areas where garbage accumulates.

Every small change can help to get rid of garbage in the oceans. What will you do to keep the world’s water clean?