"Raiders of the Lost Ark" is sensational. This awesomely entertaining adventure spectacle, directed by Steven Speilberg from an idea hatched by executive producer George Lucas, succeeds in fusing the most playful and exciting elements of Spielberg's "Jaws" and Lucas' "Star Wars" in a fresh format. It is a transcendent blend of heroic exploits, cliffhangers and chases distilled with nostalgia and wit from the pulp thrillers, comic books and Republic serials of the World War II era. "Raiders of the Lost Ark" comes as close to a Total Turn-On as most moviegoers could crave.

"Raiders," which opens today at 10 area theaters, is an exuberant joy ride that never slows. It keeps coming at you and coming at you in the spirit of its intrepid hero, Harrison Ford, as the archeologist and soldier of fortune, Indiana Jones. Known as Indy to his intimates, he overcomes fantastic odds and cheats death while preventing a sacred relic, the Ark of the Covenant, from falling into the hands of a Nazi legion supervising excavations of an ancient city near Cairo in 1936.

Our here begins his adventure in the Peruvian jungle. Apparently the leader of an expedition, he is soon reduced to a single companion as treachery or fearful superstition take their toll. He arrives at a camouflaged entrance, boldly leads the way through an elaborately boobytrapped cavern, brushes off layers of tarantulas here, averts lethal mechanisms there.

The cave is littered with skeletal remains of intruders who met grisly deaths attempting to maneuver this obstacle course. Indy appears to succeed where others have failed, but moments after he snatches the prize, a golden statue, all hell breaks loose. Running for his life, he ducks waves of darts and arrows launched from hidden recesses, hurdles a yawning abyss, survives one final act of treachery and keeps a few paces ahead of a giant boulder.

That's just for starters. The opening sequence is followed by a "breather" which reveals Indy as a mild-mannered archeology proffessor at a midwestern university. Prof. Jones' lectures seem to be especially popular with young coeds who hang on his every soft-spoken word with moony rapture. One stricken pupil has painted the words "Love" and "You" on her eyelids and flutters them in the vain hope of attracting this scholarly dreamboat.

Indy's adventures appear to originate in a somewhat shady partnership with a fellow pedagogue, Marcus Brody (Denholm Elliott), curator of the university's museum. Two representatives of U.S. Army Intelligence (Don Fellows and William Hootkins) arrive seeking information that leads to a new mission for Indy. He's asked to infiltrate the Nazi excavations under way near Cairo and attempt the recovery of the object the Germans apparently seek, the legendary Ark of the Covenant, lost for a millennium but believed to contain the remnants of the Ten Commandments. Hitler himself has supposedly initiated the project. A believer in the occult, he craved the Ark in part because of legends that its possession would bring invincible powers.

Indy's roundabout route to Egypt requires a blazing stopover in Nepal, where he's reunited with Marion Ravenwood, The Girl He Done Wrong, impersonated with delightful impulsive swagger by the lovely Karen Allen (a native of Washington). Things went bad between Indy and Marion, the daughter of his mentor, a decade earlier. Marion, running away from heartbreak, has gone Bogart's Rick one better by ending up in remotest Nepal, where she runs a gin joint and amuses herself drinking the local luts under the table.

Has an adventure movie heroine ever been discovered in a more outrageously entertaining setting? Not that I recall, and this one will be tough to top. Marion slugs Indy, but she doesn't have the luxury of nursing a grudge for long in a movie as fastpaces as "Raiders." Nazi agents are dogging Indy's footsteps, and the exlovers have to shoot their way out of Marion's saloon. Clutching an indispensable artifact retrieved by Marion's father years earlier -- a medallion which may help unlock the secret chamber containing the Ark -- hero and heroine fly on to Egypt.

Spielberg's fleetness serves more than one purpose in the context of "Raiders." It prevents the shocking and violent details from lingering long enough to become unbearable. "Raiders" is very intense, but Spielberg's timing always keeps him ahead of the audience. When he springs a shock, it's over and done with before it can be fully apprehended. He doesn't crave bloodshed either. The most gruesome single death in the story is depicted abstractly, with a cutaway shot to blood spattering a windshield.

Theiating leads of Ford and Allen are supported by wonderful work from Paul Freeman as Indy's elegant arch-rival, Ronald Lacey as a leering comic sadist from the Gestapo stock company, John Rhys-Davies as the hearty Egyptian agent and excavation team leader who infiltrates Indy at the digs. There's even a fabulous animal performance: a little spider monkey whose disarming cuteness conceals a sinister personality.

In addition to Douglas Slocombe's gorgeous photography and Michael Kahn's lickety-split editing, the production credits include a wide variety of ingenious sets by Norman Reynolds and Leslie Dilley, spiffy costumes by Deborah Nadoolman, spectacular visual effects by Richard Edlund and the optional craftsmen and a discreetly effective new score by John Williams, whose music remains, under the incessant action, unobtrusive yet indispensable.

For their parts, Lucas, Spielberg and screenwriter Lawrence Kasdan never fail to finesse the potentially monotonous material by bringing fresh gags, complications, reversals, perils and surprising payoffs to each episode. In the concluding episode, the movie takes an imaginative leap that not even two hours of ceaseless globe-trotting, thrills, chills and narrow escapes can fully prepare you for. You imagine you've been through it all with Indy, but there's always one more crisis around the bend. The finale raises the anti to stupendous, supernatural fantasy.

"Raiders" is both great fun and a splendid esthetic achievement of revitalized heroic pulp. Flipping the dial several years ago, I discovered a new kind of compilation film. It was a feature-length distillation of an old serial, "Spy Smasher," I think. The original 12 episodes had been compressed with remarkably stylish results. The continuity seemed to leapfrog from one cliffhanging situation to the next, reducing the exposition to a bare minimum. It was interesting to see how little exposition was necessary to keep this particular show rolling.

It was reminded of that compressed serial during the last hour of Lucas' "Star Wars." The first hour carried a heavy expository load, setting up almost sheer excitement in the concluding hour. The technique carried over to Irvin Kershner's direction of "The Empire Strikes Back," virtually from start to finish. Now it seems to have reached perfection in "Raiders."