Just after 1:30 a.m. on a clear night in November, Emily Harrington began ascending El Capitan, a 3,000-foot-high rock formation in California’s Yosemite National Park. She was free-climbing, pulling herself upward with her hands and feet and using ropes only as a safety precaution. This was her fourth attempt at climbing El Capitan via a path known as the Golden Gate route. Most of the climb went smoothly, although there was a point about 11 hours into her climb when she slipped and smacked her head against the rock wall. The year before, she’d fallen in the same spot and ended up going to the hospital, but this time, she checked her vital signs, bandaged her head, and began climbing once more. After 21 hours, 13 minutes, and 51 seconds, she reached the top. Harrington was the fourth person, and the first woman, to free-climb that route in under 24 hours. People typically need four to six days to scale El Capitan, no matter which route they take, and the American Alpine Club estimates that in total, only 15 to 25 climbers have free-climbed any of the routes in under 24 hours, making Harrington’s accomplishment especially impressive. “There was a lot going on in my head,” she says, “but at the same time I had this confidence deep down because I knew that I was more ready than I ever had been in my entire life.”