Kate Winslet is revealing some never-before-shared secrets from her experience filming “Titanic.”

During a panel at an advanced screening of her upcoming film “Lee” Monday, the British actress, 48, opened up about the infamous scene from the 1997 film in which her character, Rose, was floating on a door in the Atlantic Ocean while Leonardo DiCaprio’s character, Jack Dawson, eventually drowned.

“Well, that was quite an awkward tank … because, to burst the bubble, it was waist height at that time,” said Winslet, per People, describing the filming of the actual scene.

Kate Winslet described filming the infamous “Titanic” door scene.  (Felix Hörhager/picture alliance via Getty Images)

“So, first of all, I was regularly like, ‘Can I just go for a pee?’ And then I get up, get off the door, walk to the edge of the tank, sort of 20 feet away, and I literally have to fling my leg over and climb up and come and get back on the door again. It’s terrible,” she added.

“Anyway, yeah. So it was waist-high. Leo, I’m afraid to say, was kneeling down,” she added. “I shouldn’t be saying anyway. Jimmy Cameron’s [the film’s director, James Cameron] gonna be ringing me. Actually, the thing that was amazing about the edges of the tank was it was an infinity tank. So there was constant water rushing, and you could hear the constant sound of water.”

Winslet said Leonardo DiCaprio was actually kneeling in the water during the scene. (20th Century Fox/THA/Shutterstock)

Additionally, Winslet recalled the moment she sneaked into a New York City theater to watch the film.

“When it premiered in London, I was really unwell. I had terrible food poisoning, and I was actually in hospital in London, really weird. And then when it came out in the U.S., actually I was at the funeral of a boyfriend,” she said, according to People.

“I mean, it’s a horrible thing to even think about now. And, obviously, I wasn’t gonna miss that. So, I sort of missed everything around the release of ‘Titanic,’ which, I don’t know, is that the universe’s way of protecting me or just reminding me to do the things that matter?”

Kate Winslet stars in the upcoming World War II biopic “Lee.” (Getty Images)

Earlier this year, Winslet also opened up about another memorable scene in “Titanic.”

While discussing the “I’m flying” scene from the movie, in which she and DiCaprio stand on the bow of the ship, the actress admitted to Vanity Fair it looked romantic on screen, but, behind the scenes, it was anything but.

Kate Winslet told Vanity Fair kissing her “Titanic” co-star, Leonardo DiCaprio, “was not all it’s cracked up to be.” (Jason Merritt/Getty Images)

“My God, he’s quite the romancer, isn’t he? No wonder every young girl in the world wanted to be kissed by Leonardo DiCaprio,” Winslet said. “It was not all it’s cracked up to be.”

The Academy Award-winning actress called shooting the scene “a mess,” attributing the issue to many different factors.

“We kept doing this kiss, and I’ve got a lot of pale makeup on, and I would have to do our makeup checks — on both of us, between takes — and I would end up looking as though I’d been sucking a caramel chocolate bar after each take because his makeup would come off on me,” she recalled. “And he just looked like there was a bit missing from his face because there was this big pale bit from all my makeup getting onto him.

“This was a nightmare,” she added. “Leo couldn’t stop laughing, and we had to reshoot this about four times because [James Cameron] wanted a very specific light for this, obviously, and the sunsets kept changing where we were.”