The movie industry has seen a lot of firsts this summer: box office records broken, special effects reaching new heights and new stars taking their place in silver screen history.

Now it's time for another film first: a Disney (search) movie that's not for kids.

Pirates of The Caribbean: The Curse of the Black Pearl, the new swashbuckling action adventure movie that opened nationwide on Wednesday, takes the country's family film giant into uncharted waters. It's a Disney movie with a tricky PG-13 rating.

Forgoing the usual PG- or G-rating is a risk for a company that depends on youngsters for its audience, but Pirates director Gore Verbinski (search) said the movie will still draw strong crowds of all ages.

Disney originally intended to get a PG rating for the theme ride cum summer blockbuster starring Johnny Depp, according to Verbinski, but the final product ended up getting a solid PG-13 from the Motion Picture Association of America's (search) ratings board.

"The ratings board actually said, 'Don't even try, you're going to ruin the movie. It's a good movie, just take the PG-13 and be happy that you have a good movie,'" Verbinski said.

The voluntary rating system for movies was established in 1968 by the MPAA. Studios submit films to the ratings board, which grades them on how they treat topics like violence, language, nudity, sensuality and drug abuse.

Ratings are determined by what is shown on screen and not by what is implied. If a studio doesn't like the rating a film receives, it may re-edit it, submit it again and try for a different rating.

"We don't have any bad language. We don't have any sex. We have intensity," said Jerry Bruckheimer, Pirates producer. "We have these skeletons and they could be a little scary for children under 13. And we have action. There's very little blood in the movie. But the combination of the action and the skeletons, they felt, should be a PG-13."

Bruckheimer said that, despite the PG-13 rating, Pirates is quality family entertainment, but parents will have to use their judgment about whether to let their children see the film.

"I think the parents will see the movie and certain 10- or 8-year-olds will be able to see it, and others won't because it might be too intense for them. But the parents will make that decision," Bruckheimer said.

If Disney's foray into PG-13 flicks meets with success in Pirates, moviegoers may expect more of the same when Disney releases its big screen version of its famous "Haunted Mansion" ride later this year.