In 2020, Dr. Kathryn Sullivan became the first woman to descend to the Challenger Deep, the deepest point in any ocean, approximately 36,000 feet beneath the surface of the Pacific. Sullivan, who was 68 at the time, had already been a trailblazer in her career, including flying on three space shuttle missions as part of NASA’s first group of female astronauts. Yet, as Sullivan explains here, she has always been far more motivated by being able to experience these inaccessible, inhospitable places firsthand than by setting new records.

George Upton: What drives you to explore such challenging places? 

Kathryn Sullivan: It’s really just an endless curiosity. The fundamental thing that motivated me to fill out the long application to join NASA was that, if I somehow succeeded in getti...