Marcus Eriksen is the director of research for the 5 Gyres Institute, an environmental science and advocacy nonprofit organization that he founded with his wife, Anna Cummins, in 2009. With firsthand experience from over twenty ocean-crossing expeditions, he has written extensively on the impact of plastic pollution in the world’s oceans and has published research on the distribution of plastics in the subtropical gyres. In 2013, Eriksen and colleagues discovered plastic microbeads in the Great Lakes, which helped lead to a broad national campaign that culminated in the successful US Microbead-Free Waters Act of 2015. Eriksen earned a PhD in science education from the University of Southern California in 2003. That summer, fulfilling a promise made to himself as a US Marine in the 1991 Persian Gulf War, he built a raft and floated the length of the Mississippi River, which became the subject of his first book, My River Home (Beacon Press, 2007). It was that experience, and the renewed love of life, land, and sea that it brought, coupled with the never-ending trickle of plastic trash to the Gulf of Mexico, that spurred the course of his career.