The deep seas were, for millennia of human existence, something totally unknown to us. The open ocean was only something to be braved in order to make a crossing. Onlyl recently in human history has technology let us examine the deepest parts of the ocean. Every year, new discoveries are made about these deepest depths. Scientists are finding new species, new ecologies, and new mineral deposits. Helen Scales shows the incredible characteristics of the abyss, and documents the threats facing it. Moreover, she shows us that the threat to this ecosystem is also a threat to the whole planet: vast quantities of carbon are stored in the seabed, and extractive mining operations risk releasing that carbon into our already overheating atmosphere. A must read for any budding oceanographer or marine biologist, and a fascinating look at a part of the world that we still know so little about.