Consider the Octopus by Nora Raleigh Baskin
JB Barnes is looking forward to spending the summer hanging out on the beach. But his mother, a scientist, asks him to join her aboard a research ship where he'll spend his summer seasick and bored, staring out at the endless plastic, microbeads, and other floating debris that make up the Great Pacific Garbage Pile. Miles away, twelve-year-old Sidney is trying to come up with an activity worthy of convincing her overprotective parents that she can skip camp. When Jeremy is asked to find the contact info for a list of important scientists and invite them to attend a last-minute Emergency Global Summit, he's excited to have a chance to do something. But how could he know that the Sidney Miller he emailed was not the famous marine biologist, but a girl posting blogs from her bedroom-let alone that she would come aboard the ship? This is a comedy of errors, mistaken identity, and synchronicity. Above all, it is a heartfelt story about friendship and the power of kids to step up and save our oceans and our Earth, perfect for fans of Lynne Kelly's Song for a Whale.