The story of a piece of litter doesn’t end at your curbside. Every year, millions of tons of trash find their way down storm drains and rivers to the ocean. Ocean currents take over from there, carrying man-made stuff thousands of miles away to far-flung corners of the planet—even to places otherwise thought to be untouched by people. And that makes marine debris difficult to clean up. Here’s what you need to know about the trash that’s piling up on Pacific Northwest beaches and around the world’s oceans.