This is an examination of how the seas darkest recesses are being illuminated to reveal a world teeming with life, lost artworks and treasures. In the company of scientists and explorers, the author, a Pulitzer Prize winner, describes how modern technology, some of which was developed for Cold War espionage, is uncovering information about ancient life forms, historic events such as the sinking of the Titanic, and current environmental dangers that could have devastating long-term effects.