The 1993 drama, about a mute pianist and her daughter, was a huge hit at the box office and won Oscars for its two stars Hunter and Anna Paquin, as well as a screenplay award for Campion.
However, the moviemaker insists she made the wrong decision about the ending, when Hunter's character, Ada, dives into the ocean with her foot deliberately tangled in a rope after her beloved piano is thrown from a boat.
Ada subsequently resurfaces, but Campion now feels the film would have been better if she had died.
She tells Britain's Radio Times, "I thought some of it (The Piano) was really good, but I thought, 'For freaking hell's sake, she should have stayed under there (the water).' It would be more real, wouldn't it? It would be better. I didn't have the nerve at the time."
However, Hunter insists she is glad Campion didn't change the film's conclusion: "That was something Jane toyed with when we shot the movie, to end it there. And she's still thinking about it! Me, I love that it's a reverie for Ada, not a nightmare."