Don Walsh and Jacques Piccard both risked their lives to descend that deep, and only the former is still alive.

CNN: STORY HIGHLIGHTS

In 1960 Don Walsh, along with Jacques Piccard, undertook an eight-and-a-half hour decent in the bathyscaphe Trieste to the deepest part of the ocean, the 10, 911 metre (36, 000ft) Challenger's Deep in the Mariana Trench off the coast of the Phillipines.

BBC: Voyage to the 'real' North Pole

In 1960, Piccard's father, Jacques, descended seven miles beneath the Pacific Ocean in another pressurized module to set a deep-dive record that has been matched only twice.

WSJ: A Solar-Powered Plane Travels Light | WSJ. Magazine May 2013