LOS ANGELES – As the final credits for the latest “Pirates of the Caribbean” installment crawled skyward, I kept waiting to see some author’s name scroll by. Surely, I thought, this behemoth of a story was adapted from some fantasy epic. Logging more water miles than Magellan, “At World’s End” picks up the tenuously hashed-out plot elements from the second film and piles on even more romances, locales and characters by the shipful. Much like the “Lord of the Rings” trilogy, “World’s End” plays like an earnest effort to cram the sprawling mythology of a book series into a few hours of celluloid.

Only, as we all know, this movie isn’t based on beloved fantasy novels. Why the film’s creators took a simple amusement park concept and inundated it with J.K. Rowling-levels of mythology is a mystery.

These sloppily interwoven plot threads, which were difficult to keep track of in the sequel, are downright baffling in “World’s End.” The film’s disturbing first images – of downtrodden pirate sympathizers being hanged and disposed of – quickly establish the be-wigged Brits as militant, unstoppable thwarters of all things rum and merriment. With the English in control of Davy Jones and his ship, the Flying Dutchman, the seas are being purged of piracy. Apparently, a convening of the Pirate Brethren, an assembly of the world’s nine leading pirate captains, is the only way to stop the ruthless Lord Beckett.

This motivation takes our sundry heroes – and by now the pirates are unquestionably heroes – from one exotic setting to the next, each one a digital masterpiece. Singapore, where Chow Yun-Fat’s Capt. Sao Feng reigns, is an intricate Oriental translation of the Caribbean pirate towns, and retains the look and feel of an “imagineered” Disney theme park ride. As a “Pirates” newcomer, Yun-Fat’s over-the-topness is actually a welcome addition to a film dripping with familiar faces that have devolved into stale caricatures.

Geoffrey Rush, as the sequel hinted, is back in top form as Capt. Barbossa and he, in tandem with the tentacled Bill Nighy, make the action-less scenes watchable. There’s a tender, quiet moment between Nighy’s Davy Jones and the Caribbean mystic Tia Dalma (Naomie Harris) that nearly makes you forget the whole thing is busting at the seams. If it weren’t for Nighy, Rush and the handful of British character actors, this ship would have surely sunk. Johnny Depp’s in there, too, of course, but this time around his Capt. Jack Sparrow seems more contrived than ever before, going through the movements like an animatronic. His frequent verbal sparring with hallucinated Sparrow clones is clever – nearly redeeming – but Barbossa’s scene-stealing monkey (which surely got a big check this time around) had more character than Depp’s flouncing jester.

Orlando Bloom and Keira Knightly had enough to do, but the couple’s on-and-off romance comes off as an afterthought. An easy on the eyes afterthought, though.

As one befuddled Englishman asks after Sparrow has made impossible escape No. 619 of the series: “Do you think he plans it all out, or just makes it up as he goes along?” You’ll leave thinking the same of the movie.

It’s best, then, to enjoy “At World’s End” as you would the ride that spawned this waterlogged series: Mindlessly float through and marvel at the passing action and scenery, all deserving of the Jerry Bruckheimer Seal of Approval. Oh, and as I’m sure Sparrow himself would agree, a little rum wouldn’t hurt.