The ocean's deep-sea bed is scattered with ancient rocks, each about the size of a closed fist, called "polymetallic nodules." Elsewhere, along active and inactive hydrothermal vents and the deep ...

Deep-sea mining targets mineral deposits on the ocean floor, typically at depths of 3,000–6,000 meters. Most attention focuses on polymetallic nodules—potato-sized rocks lying on abyssal plains—and on ...