At a recent Ivy League swim meet, spectators were split over which side of the pool to look at. 

At one end, several women jackknifed their bodies in flip turns for the final lap of the 500-meter freestyle. Their furious kicks churned the water and left white vapor trails in the sky-blue pool. On the other end, a swimmer named Lia Thomas had already finished and broken the Harvard pool record. In the 7.5 seconds it took for the second-place swimmer to arrive, Ms. Thomas adjusted her swimming cap, took off her goggles, and took in the scene around her. In an online video of the race, which has been viewed over 5 million times, a visible banner near Ms. Thomas’s lane bears the slogan “8 Against Hate.” 

The sign, meant to oppose hatred of any kind by the eight Ivy League Universities, is a form of support for Ms. Thomas, a transgender woman. She’s made a splash not just in her sport but in the tempestuous culture wars. The fifth-year senior at the University of Pennsylvania has tallied record-setting wins in her first season competing in the women’s category. In a new and rare interview, Ms. Thomas told Sports Illustrated, “I want to swim and compete as who I am.”