These amphipods were discovered by scientists from the University of Aberdeen in waters more than 4 miles deep, north of New Zealand. Similar shrimplike crawlers may lurk at the bottom of the Challenger Deep. Oceanlab/University of Aberdeen/AP hide caption

itoggle caption Oceanlab/University of Aberdeen/AP

James Cameron traveled to the bottom of the Mariana Trench last year — a depth of nearly seven miles. Courtesy of Mark Thiessen/National Geographic hide caption

itoggle caption Courtesy of Mark Thiessen/National Geographic