Plastic: it’s used to make everything from drink bottles and bags to toys and toothbrushes. But what happens when it ends up where it doesn’t belong–like in the Pacific Ocean? How does it affect ocean life? Is it dangerous? And exactly how much is out there?

A team of researchers went on a scientific expedition to find out. They explored the Great Pacific Garbage Patch, where millions of pieces of plastic have collected. The plastic has drifted there from rivers, beaches, and ocean traffic all over the world. Most of it has broken down into tiny pieces the size of confetti.

For nearly three weeks at sea, researchers gathered bits of plastic and ocean organisms. These samples helped them learn more about the effects of plastic in the ocean. Follow along on the expedition to find out how scientists studied the Garbage Patch–and what alarming discoveries they made.