At the pool with freestyle phenom Katie Ledecky

Katie Ledecky was one of the most triumphant athletes of the Rio Olympics. The 19-year-old swimmer overwhelmed her competition; in the 800-meter race, she finished nearly a pool length ahead of second place. Known for relentless training and humility, she will forego endorsement deals to attend Stanford University this fall. Margaret Warner met her in Bethesda, Maryland, at her high school pool.