Which of us, while sitting at the edge of the ocean and gazing toward the horizon, hasn't shivered to imagine being drawn out to sea, getting lost and ending up a tiny forgotten speck in the middle of nowhere, shouting at the sky? As potentially panic-inducing as this vision may be, there's also something alluring about it. It's like standing on the edge of a cliff and imagining that fatal leap into the unknown. And in the heart-stopping ocean and desert-island scenes that constitute the core of Cast Away, Tom Hanks, in collaboration with the director Robert Zemeckis and the screenwriter William Broyles Jr., brings those visions thrillingly to life.

With a bravura mastery of tone and timing, Cast Away sweeps us out to sea and washes us ashore on a tiny deserted island in the Pacific. We remain stranded there just long enough to be given a deep gulp of what it's like to have to restart civilization from scratch. Just in time for dinner, however, we're whisked back to safety and to tables piled high with supermarket goodies and a life that oddly and sadly seems banal and superfluous compared to what has gone before.Cast Away, like Titanic, awes us with its sheer oceanic sweep and its cosmic apprehension of human insignificance.

The center of the film is a gripping evocation of the unbearable loneliness and terror of ultimate abandonment. This modern-day Robinson Crusoe, Chuck Noland (Mr. Hanks), is a voluble, time-obsessed efficiency expert for Federal Express. Shortly before boarding a plane that plunges him into the Pacific, he and his girlfriend, Kelly (Helen Hunt), exchange gifts: an engagement ring from Chuck, her grandfather's pocket watch (with her picture inside) from Kelly. Marooned with only the timepiece to remind him of home, Chuck finds himself facing only one deadline, the race to survive in the face of starvation, dehydration and natural disaster.

Cast Away is everything this year's other man-against-nature blockbuster, The Perfect Storm, was not. The earlier film huffed and puffed to evoke a similarly elemental struggle in the traditional Hollywood ways, with strenuously grandiose music and unrealistic computer-generated special effects. Cast Away also has its quotient of technological trickery, but one of the movie's wonders is that everything looks and feels so remarkably real. It also knows when to turn down the volume. The most devastating sequences, instead of flooding us with music, suspend the soundtrack and forgo even language to allow the sounds of nature to take over. All we hear from Mr. Hanks are the grunts and howls of a man exertng himself to stay alive against a backdrop of the roaring ocean and the wind eerily whistling outside the cave Chuck adopts as a shelter. Ultimate isolation, the movie reminds us, doesn't have a soundtrack except what the environment churns up along with our heartbeats and the voices chattering in our minds.

Once again, Mr. Hanks portrays a spirited Everyman, at once deeply likable and profoundly ordinary. If his globe-trotting character, who early in the film is shown haranguing Russian employees at a FedEx depot in Moscow, isn't exactly like you and me in his background and tastes (he happens to be an Elvis Presley fanatic), he embodies enough parts of other people to be utterly recognizable.

Mr. Hanks's likability has everything to do with the ease with which he pours the childlike side of himself into his performances. Even at moments of maximum stress, the qualities that shine through are infectious curiosity, ebullience and native optimism, along with an instinctive resourcefulness.

Once Chuck is aboard a FedEx plane flying over the Pacific, an escalating sense of dread takes over as the aircraft gives a warning shudder. What follows is the scariest, most believable plane crash ever filmed as the aircraft begins splitting apart and plummets in a whirling roar amid a violent thunderstorm. It is so real you can almost feel the metal body of the aircraft shaking violently as it is wrenched apart. Crashing into the ocean, Chuck is plunged underwater. Rising to the surface, he finds himself surrounded by pieces of the burning aircraft illuminating utter blackness in a furious storm.

Chuck, close to exhaustion, has drifted onto the shore of a tiny tropical island. After that, the movie makes each lesson in survival — from pounding open a coconut, building a fire to a first frustrated attempt at an escape — an agonizing, often bloody, sometimes life-threatening ritual. The world in which he finds himself, a pristine island amid a turquoise sea, is as dazzlingly beautiful as it is treacherous.

The screenplay's master stroke has Chuck revert to childhood through the creation of an imaginary companion so he can survive psychically. Painting a face (in his own blood) on a white volleyball extracted from a FedEx package that washes up on shore, he turns Wilson (as he calls the ball) into a fellow survivor, confidant and collaborator in an escape plan. Anyone who recalls being a very young child and clutching a doll that embodies comfort and companionship in times of loneliness and insecurity will relate to the wrenching scenes in which Chuck clings to Wilson for emotional support.

The volleyball is one of many practical uses Chuck is able to make from the washed-up items (many of them Christmas presents) in FedEx packages that at first seem useless but become essential survival tools. A pair of figure skates becomes both a knife and a tool for removing an infected tooth in an excruciating scene of do-it-yourself dentistry. Videotapes become ropes for an escape raft, and the netting in a fancy dress a fishing net.

Finally, the movie fades out and a title informs that four years have passed. In the intervening years, Chuck has become gaunt, shaggy, nut-brown and camped in a lair embellished with his own cave drawings. Mr. Hanks lost more than 50 pounds for this section of the film (Mr. Zemeckis completed What Lies Beneath in the interim), and the actor's physical transformation is as startling as the fattened-up Robert De Niro in the later scenes of Raging Bull.

Ultimately Cast Away has to end somewhere since it's has an attenuated love story it needs to resolve. Once Chuck is saved, he wears the faraway expression of a man whose unusual experience has separated him from others. For the rest of his life, we sense, an essential part of him will still be living alone on that island.