Jacobson said minor changes have been made periodically through the years to update and improve characters and effects. But this is the first time changes have been made that affect the ride's story.
A new plot line derived from the movies will be woven in: The evil pirates are looking for Sparrow, he's trying to stay one step ahead of them, and both are looking for treasure. Sparrow will make his first appearance at the ride's well scene.
"The captain at the well is dunking the mayor, asking him if he knows where Jack Sparrow is," Jacobson said. "In the shadows, just outside of the scene, is going to be the figure of Jack Sparrow."
The Davy Jones character will be "a brand new special effect and a brand new way of presenting a character in the ride," Jacobson said.
Other changes will involve updating the decades-old sound and lighting systems with 21st-century technology, he said.
The sequel, produced by Walt Disney Pictures, is set to premiere at Disneyland in late June, with a gala opening. Disney spokesman David Brady said it is too early to say whether any special events, such as personal appearances by Depp or other stars of the movie, would be held at Disney World when the film opens here and nationwide July 7.