Every year, millions of metric tons of plastic debris winds up in our oceans, wreaking havoc on marine ecosystems. A recent study found that up to 95 percent of that plastic waste enters oceans through 10 different rivers around the world. This is an alarming prospect, but also a promising one as it tells us where we must act in order to stop plastic from polluting the ocean. While preventing such an unthinkable amount of plastic from entering the oceans seems like a mammoth task, the bright side is that we now know where to start.