The Dark Frontier: Unlocking the Secrets of the Deep Sea

The deep sea “may well be the largest, most diverse, most consequential habitat on Earth,” writes marine microbiologist Marlow in his moving debut exploration. Still largely unexplored, the deep sea—the vast, cold zone below the ocean’s surface where no sunlight reaches—is at a “precarious inflection point,” he contends, as human activity threatens its biodiversity and other key features. Attempting to understand this immense habitat before it’s forever changed, Marlow takes numerous research trips into the Atlantic and Pacific oceans, including an expedition in the “world’s most scientifically advanced submersible,” Alvin, which brings him thousands of meters below the surface of the Caribbean Sea. He traces the history of deep-sea exploration, from the discovery in the mid-1800s that the ocean’s depths were filled with life to more recent revelations, like hydrothermal vents (fissures in the seafloor that spew heated, mineral-rich water). Elsewhere, he explains how the deep sea impacts terrestrial life by absorbing carbon from the atmosphere, and the threats posed by such exploitative activities as seabed mining and overfishing. Marlow’s fascination with underwater environments is palpable throughout, as he studies microbes that can exist by metabolizing methane, and discovers hidden ecosystems of strange fish, crustaceans, and worms (“It was amazing to think how these bizarre bodies came to be, molded by the gradual yet uncompromising scalpel of evolution”). This is science writing at its finest. (Apr.)