To this day, the least explored part of Earth lies beneath the ocean. Covering more than 70 percent of the planet, the oceans hold many secrets that scientists and adventurers continue to uncover. From the discovery of the depths of Challenger Deep within the Mariana Trench to director James Cameron's expedition to the ocean floor, the adventures beneath the sea are many. Readers can dive into the fascinating explorations with full-color photographs, descriptive sidebars, and plenty of mystery for future, curious scientists to ponder!