In late 2012, just a week after Hurricane Sandy flooded the streets of the quickly gentrifying Gowanus neighborhood in Brooklyn, Outside sent a reporter to an obstacle race at Brooklyn Boulders (BKB) as part of a story on indoor climbing called “The Next Urban Sports Craze.” The raucous scene at the gym, as described by Outside, was peak millennial cool, with the theme song to Teenage Mutant Ninja Turtles blasting over speakers, climbers and slackliners competing for prizes that included free beer, and eager climbers turned away at the door because the event was full, despite the...