Challenges of Getting to 'Challenger Deep'

Sixty years ago, on 23 January 1960, then–U.S. Navy Lieutenant Don Walsh and Swiss oceanographer Jacques Piccard descended 35,814 feet to the lowest known spot on Earth—the Pacific Ocean's Challenger Deep—in the bathyscaphe Trieste. In the years since their accomplishment, only four other humans have reached Challenger Deep. Compare that to the somewhat analogous achievement of Sir Edmund Hillary and Tenzing Norgay on 29 May 1953, when they reached the 29,029-foot summit of Mount Everest. Since then, nearly 9,000 climbers have reached the top.