Over 70 percent of Earth is water, but what exactly is in the oceans and lakes that surround us? In this series, readers take an in-depth look at the many creatures that spend their lives completely--or partially--underwater, from fish and mammals that swim in the ocean to sea plants and algae that grow on the ocean floor. Vivid photographs allow readers to immerse themselves in the world of marine wildlife. They also learn the importance of protecting these sea creatures and their homes against global warming, to ensure a safe future for humans and animals alike.