Although the deep sea constitutes the single largest habitat on Earth, we understand very little of what exists there. Only 5 percent of the ocean's floor, for instance, has been mapped in any degree of detail. Over the past 25 years, meanwhile, a new creature has been noted nearly every other week. Nevertheless, as Nouvian is quick to point out, that most uncharted of territories is also the least protected. Because we cannot see it, because we're unaware of what is there, she argues, we cannot understand or care about the irreparable damage we are causing. When tropical reefs disappear, it's easy to see the effects our boats, trash and pollution have and to act accordingly. When deep-sea reefs disappear, only a handful of specialized scientists realize what that means.