June 8, 2001 | The thin line between boisterous fun and games and bombastic sound and fury is repeatedly crossed, and frequently smudged, during Atlantis: The Lost Empire, the latest animated feature from Walt Disney Productions.

Give this much to the creative folks at the Mouse Factory: After years of generating a steady cash flow from formulaic musical-comedy cartoons, they're trying their darnedest to diversify their product line. After scoring with computer-generated animation (Toy Story, Dinosaur) and Loony-Tuney flavored high jinks (The Emperor's New Groove), they've hit upon the novel notion -well, OK, novel for Disney - of mounting a lavishly detailed widescreen epic that tells a straight-ahead fantasy-adventure story without relying on original songs, precocious kids or cuddly, chattering animals.

Instead of taking their cues from the conventions established by Uncle Walt, co-directors Gary Trousdale and Kirk Wise and screenwriter Tab Murphy have concocted an eclectic mix of classic pulp fiction (heavy on the Edgar Rice Burroughs, with a side order of H. Rider Haggard), Japanese anime razzle-dazzle, nondenominational mysticism (think Edgar Cayce by way of Lost Horizon) and graphic-novel conceptualization. All this, plus great big hunks of Jules Verne. Specifically, Verne's 20,000 Leagues Under the Sea, which, not so coincidentally, the Disney studio filmed as a live-action feature back in 1954.

Instead of journeying aboard the Nautilus with Captain Nemo, the adventurers in Atlantis set out in a state-of-the-art submarine known as the Ulysses. Mind you, state-of-the-art is a relative term here, since the movie is supposed to be set in 1914. But, then again, 1914 is a relative date as well, judging from the anachronistic technology that becomes increasingly evident as the story progresses. (Hey, it's a fantasy adventure, remember?)

The Ulysses expedition is launched to find the fabled lost city of Atlantis, and funded by an eccentric billionaire, Preston B. Whitmore (voiced by John Mahoney), who's obviously a pioneer in the field of equal-opportunity employment. In addition to hiring Commander Rourke (James Garner), a cunning mercenary, to lead the mission, Whitmore also employs such colorful characters as Helga (Claudia Christian), a tough-chick second-in-command; Vinny (Don Novello), a dryly witty Italian explosives expert; Dr. Sweet (Phil Morris), a hunky African-American physician; and Audrey (Jacqueline Obradors), a Latina mechanic.

But the true hero of the piece is Milo James Thatch (Michael J. Fox), a callow cartographer and linguist who's along for the ride primarily because his late grandfather was an expert in all things Atlantean. Thatch provides invaluable interpretive services when Team Ulysses finds a subterranean route to the long-lost empire. Just as important, Thatch also helps to rally the blue-hued, gentle-spirited natives - including the beautiful Princess Kida (Cree Summer), daughter of the ancient city's ailing King (Leonard Nimoy) - when Rourke and Hegla try to snatch the magical crystals that provide energy and enlightenment for the Atlanteans.

Atlantis isn't quite a complete break from the traditions of classic Disney animated features. Many of the lead characters - including Milo, who looks like a slightly more grown-up version of John, the bespectacled lost boy of Peter Pan - could have jumped right out of Uncle Walt's inkwell. And a few of the minor characters, including a crusty cook (the late Jim Varney) and the aptly named Mole (Corey Burton) are so broadly rendered, they might as well be anthropomorphized forest critters.

But never mind: The real problem here isn't the residue of movies past. What makes Atlantis something less than an unalloyed delight is the overwhelming and ultimately overbearing busyness of the movie. This is especially true in the last half hour or so, when there is so much going on, and the widescreen frames are cluttered with so much material, that Atlantis plays like an unpleasantly revved-up rollercoaster ride, or an overly caffeinated retread of Raiders of the Lost Ark.

I know it may sound odd, and more than a little ungrateful, to complain there's too much activity in an action film, especially when it's an animated action film. But Atlantis feels like the work of people who didn't entirely trust the magic of their narrative or the wonder of their imagery, and who felt obliged to pelt you with everything but the kitchen sink while you experience sensory overload. They appear to have forgotten that, when extended so long, so relentlessly, even a rollercoaster ride can be more exhausting than exhilarating.

By the way: Parents, take heed of the PG rating. Some of this stuff may very well be too intense for very small children. And for quite a few adults.