The Underworld: Journeys to the Depths of the Ocean

by Susan Casey

The deepest of them is the Mariana Trench, a fifteen-hundred-mile-long, forty-four-mile-wide gash in the seabed, near Guam. It’s home to the 35,876-foot Challenger Deep, the ocean’s absolute nadir. By comparison, Mount Everest is 29,029 feet high.