The sequence from the 1997 blockbuster sees Rose (Winslet) climb on top of a floating door after the famed ocean liner plunged below the icy waves, all while her lover Jack (Leonardo DiCaprio) clings on, though the 48-year-old actress has now admitted the making of the scene was not as impressive as it appears on screen.
During an appearance on the 'Happy Sad Confused' podcast, she told host Josh Horowitz: "Well that was quite an awkward tank, that one.
"To burst a bubble, it was waist-height, that tank. So first of all, I was regularly like, 'Ugh, can I just go for a pee,' and then I'd get up, get off the door, walk to the edge of the tank that was sort of 20 feet away, and I'd literally have to fling my leg over and climb out the tank and go for a pee and then come back and crawl on the door again."
The 'Avatar: The Way of Water' star joked she shouldn't be exposing these moviemaking secrets because director James Cameron would hound her for doing so.
She continued: "It's terrible to admit these things ... Leo is, I'm afraid, kneeling down on the bottom of the tank. I shouldn't be saying any of these things. James Cameron's gonna be ringing me like, 'Why are you telling them all that?'"
Winslet added the last 20 minutes of the picture were shot entirely with Automated Dialogue Replacement (A.D.R.) because the constant rushing of water from the tank drowned out both her and DiCaprio's lines.
She said: "The thing that was amazing about the edges of the tank was that it was an infinity tank, so there was constant water rushing, and you could hear the constant sound of water."
The scene has long been a point of contention over whether Jack could have fit on the door alongside Rose instead of succumbing to his watery grave and the actress joked her co-star "probably got PTSD from the whole thing".