Below the Edge of Darkness takes readers deep into our planet’s oceans as Widder pursues her questions about one of the most important and widely used forms of communication in nature. In the process, she reveals hidden worlds and a dazzling menagerie of behaviors and animals, from microbes to leviathans, many never before seen or, like the legendary giant squid, never before filmed in their deep-sea lairs. Alongside Widder, we experience life-and-death equipment malfunctions and witness breakthroughs in technology and understanding, all set against a growing awareness of the deteriorating health of our largest and least understood ecosystem. A thrilling adventure story as well as a scientific revelation, Below the Edge of Darkness reckons with the complicated and sometimes dangerous realities of exploration. Widder shows us how when we push our boundaries and expand our worlds, discovery and wonder follow. These are the ultimate keys to the ocean’s salvation—and thus to our future on this planet.