Credit: Paramount Pictures/AP Photo

Kate Winslet cringed at the sight of herself back on the big screen in the 3-D version of "Titanic," the blockbuster film that turned a barely known English actress into a megastar over 15 years ago.

"The second it came up I literally went, 'make it stop, make it stop, turn it off. I'm blocking it off. Do I really sound like that? Did I really look like that?' It's very, very bizarre," Winslet said when the filmmakers showed her a clip of the movie. "It's like someone saying, 'OK here's a home video we made of you 16 years ago and now we're gonna make you watch yourself in 3-D.'"

Winslet and Leonardo DiCaprio captivated audiences as the star-crossed lovers Rose DeWitt Bukater, a first class debutante, and Jack Dawson, the lowly boy from steerage, in the 1997 epic romance " Titanic." Now, timed to the 100th anniversary of the Titanic's sinking, 15 years after the original film came out, 300 computer artists have spent 750,000 man hours to give "Titanic" a third dimension - which includes some of the film's most intimate scenes.

In the original movie, Winslet, who was just 21 at the time of filming, appears naked while DiCaprio's character draws her portrait. While "Titanic 3-D" is the first of her films Winslet said she is allowing her two children to watch, the actress jokingly said she would have their eyes covered during the nude scene.

"I already have the people planned for the hands-over-the-eyes moment," Winslet said. "I'm gonna be doing eyes and someone else is gonna be doing ears, because it's not just about what they're seeing but what they're hearing as well."

But the most iconic scene from the film is when Jack and Kate meet at the bow of the ill-fated ship. It  has earned a place in cinematic history, but has haunted the movie's leading lady over the years.

"I can never get on a boat without someone saying to me, 'Oh would you mind? Can we just go on the front? Just for my mom. I literally offer it up now, whenever I got on a boat, I'm like, 'OK, Come on, form a line. Here we go,'"  Winslet said. "But it does happen and it will happen for the rest of the life I'm sure."

What moviegoers saw might have been magic - Winslet flying on the boat's bow and exchanging a passionate kiss with DiCaprio surrounded by a spectacular sunset - but the filming was far less romantic and glamorous, Winslet revealed.

"I look back on it and all I remember it was always a rush. We shot it four or five times, if not more actually, just because [director]  James Cameron wanted the option of various different lights in the sky. They're would always be this terrible rush, like, 'Oh my god, the sun is in the perfect spot. Come on, Kate, come on Leo, up onto the bow,'" she recalled. "To be honest to you, Leo and I were like, 'Oh my god, here we go again.' I'm not kidding you."

The actress also said that the conditions during shooting made everyone miserable.

"We would cry on each others' shoulders. We're freezing. We're tired. But that was all of us. It wasn't just me and Leo, that was all of the cast and the crew," Winslet said. "We were all very much, pardon the pun, in the same boat. "

But they got it right and made one of the biggest movies of all time. "Titanic" broke records, becoming the first film to gross more than $1 billion at the box office. Now its 3-D version will hit the big screen again on April 4.

"It does look spectacular I have to say…you sort of feel like you're on the fairground ride…as opposed to sitting back and watching the spectacle, you're really immersed in it," she said.

The movie solidified Winslet (and DiCaprio) as a force to be reckoned with in Hollywood. The powerhouse actress has become a regular on the awards circuit. The youngest actress to be nominated for six Academy Awards, she won the coveted Best Actress Oscar statuette for her role in 2009's "The Reader."

But even now, over a decade later, Winslet said she often finds herself wondering how she ever landed the role of Rose in "Titanic."

"I did every day think, 'How did I get this part? How did I get this part? How did I get this part?' You know, Kate from Reading, [England]," Winslet said. "People would say to me, 'What's gonna happen, your life is gonna completely change and I would just think, 'No it's not! No it's not!' And I would almost become offended, like I took it personally that I wouldn't be strong enough to handle whatever the world threw at me. The reality is I did try to fight the change, but it did change."

"I kept my head, I mean I've never been one of those people who ended up in the gutter with sick in my hair," she added.

Winslet is grateful that she became a megastar 15 years ago, before the onslaught of a 24-hour celebrity news culture, social media and paparazzi that push the bounds of privacy.

"I think now when young people are sort of thrust into the public eye like that, they're almost told they're successful and told they're famous before they even really know how to compute how that means, even before they can understand who they really are," she said. "I think there's a lot of pressure on young people to really be the thing that everyone is telling them that they are, opposed to discovering it for themselves."

ABC News' Nick Watt contributed to this report

Watch " Nightline" tonight at 11:35 p.m. ET/PT " Good Morning America" tomorrow fat 7 a.m. ET/PT for more with Kate Winslet.