In Thérèse Raquin—spoiler alert!—the title character, who is bound to a loveless marriage, engages in a dangerous affair with another man, and the two plot to kill her husband. Trouble is… Thérèse (played in the recent revival by Keira Knightley) and her lover Laurent (Matt Ryan) drown Camille Raquin (Gabriel Ebert) on a boat trip down the river, and all the action is played out onstage—quite the challenge for the show’s scenic designer.

Yet, Beowulf Boritt earned a 2016 Tony Awards nomination for his work, and the biggest question on audience’s minds was: How did he create an onstage river at Studio 54 deep enough for Ebert’s character to drown?

He’s had experience with water before. “I had done a show for the Roundabout a couple years ago called If There Is I Haven’t Found It Yet with water in it, where we had a lot of problems, and it leaked forever,” he admits. “So when we realized we wanted to do real water and make it deep enough that you can row a boat in it and throw someone in it, I emailed [Roundabout Theatre Company general manager] Sydney Beers, and I said, ‘Sydney, we need to have a talk about the W word.’ I knew that they were going to resist it for a lot of good reasons, and we had a long careful talk.

“But it was a challenge. We had to check and make sure that the theatre floor could actually hold the weight of the water because there was a lot of water. It was sort of raked [at the bottom], so it could get deep enough, and then [it was created with] a layer of rubber [followed by] a layer of steel so that we couldn’t puncture the rubber. Then another layer of rubber [was placed] on top of that because there’s going to be a lot of violence in it. Knock on wood, we never leaked. I think one day somebody did something wrong, and we got a lot of water spill over the edge into the trap room, but it wasn’t a leak. Other than that, it was really great.”

Leakage wasn’t the only obstacle, though. Because water is clear, and Boritt was attempting to create a bottomless river, he had to ensure that audiences in the mezzanine and balcony could not see the rubber pool liner at the bottom. It would “lose all the magic,” Boritt says.

“What I had them do at the Roundabout is: We bought a whole lot of really, really reflective, shiny rubber, so it would be like a black mirror,” he explains. “The shop kept saying, ‘We’re not going to need to do this.’ And, I said, ‘I’ve done this before. We’re going to need to do it.’ We got in there, and, bizarrely, we just got lucky. It’s got to be physics and how the light refracts off of it… You couldn’t see through the water. We checked from every seat in the balcony; we checked all over the orchestra, but we never needed to put the shiny rubber in because you actually couldn’t see through for some reason.

“Even from the balcony, when Gabe Ebert went into the water, he just disappeared. You couldn’t see that he was there. It was about three-feet deep in the middle, but not really deep enough for him to disappear, and yet the light refracting off the water somehow did it, and we got our magic trick.”

When it was all said and done, and the production played its final performance January 3, 2016, Boritt and his team celebrated with a pool party. “There are a lot of pictures floating around on my Facebook page of me and my assistants floating around in the pool with swimmies on…and rowing around in the boat,” he says. “We went swimming quite a few times, actually!”

Michael Gioia is the Features Manager at Playbill.com. Follow him on Twitter at @PlaybillMichael.