Marcus Eriksen made a huge impression on me when I first met him. He is an environmental scientist, educator and author as part of his day job. On the side, he's built rafts out of junk, floated down the Mississippi river for days on said raft, writes books about his adventures and advocates for the environment. He has been an outspoken and forthright advocate for the environment, particularly the elimination of plastics in the oceans. Most importantly, his efforts have gotten results, notably in a law prohibiting micro-beads in cosmetics.