Tracy Spiridakos spent a lot of time underwater for the February 23 episode of Chicago P.D. In “Still Water,” Detective Hailey Upton is out for a jog when she witnesses a horrible car crash and risks her own life to save the passengers. “I feel like everyone in the unit would probably have a similar response to jump in truthfully,” Spiridakos tells TV Insider. “Selfishly, I’m happy that it was me ’cause it was a lot of fun. It was a really cool episode.” Lori Allen/NBC And when she says “jump in,” she means it: Upton jumps into the river to try to save whoever’s in the car. As you can tell from the photos above and the behind-the-scenes video below, it’s night, it’s Chicago, and it’s freezing. In other words, it looks brutal. “It was definitely intense,” Spiridakos says. “The jumping into the river,...