A moment of sympathy, please, for the unlucky folks charged to make a movie out of a best-selling book. Although the allure of a built-in audience must be tempting, few things are as daunting as the fury of leagues of devoted readers ready to nitpick every single character alteration or dropped comma. (Submitted for evidence: the faithful to a ridiculous fault Sin City, which is already spawning websites devoted to detailing even the slightest change of camera angles or differently shaped yellow-colored blood puddle.) Luckily for the filmmakers, Sahara, an intensely amiable Indiana Jones clone and hopeful franchise starter, may be one of the few cases where the phrase, "the book was better," actually doesn't apply. Much to the chagrin of the author (who has reportedly threatened legal action), it wisely ditches close to everything of the ponderous source material, substituting an easygoing buddy movie vibe that's difficult not to amble along with. You may feel guilty afterwards, but it's tough not to dig the ride.

Thankfully, only the barest plot and character elements are held over from Clive Cussler's virtually unreadable doorstop of a novel, which is the kind of tech-heavy, mondo-macho potboiler that stewardesses must get tired of sweeping up after every flight. (Actual sample passage: "This day, the temperature rose from 15 degrees C (60 degrees F) to 35 degrees C (95 degrees F) in three hours, topping off during the hottest part of the afternoon at 46 degrees C (114 degrees F).") What still remains: Matthew McConaughey is the wonderfully named Dirk Pitt, a ludicrously rad underwater explorer/rare-car enthusiast/secret agent/master of languages/all-around stud who, along with faithful companion/hetero life partner Steve Zahn, gets caught up in a sinister desert plot involving Civil War battleships, ocean-killing water pollution, toxic waste, slithery French industrialists, feuding generals, and Lord knows what else. McConaughey's THC-saturated, lounge-lizardy persona may be far from the standard Man of Action template, but it adds a wobbly nonchalance to his various acts of over the top derring-do.

Refreshingly, this unpredictability extends to the rest of the cast as well. Zahn's sidekick character proves to be just as competent as the lead, Penélope Cruz' hot scientist babe is allowed to do more than wear glasses and scream, and the ethnic characters in the background are generously granted more than one character trait apiece. (The extended cameos by such venerable character actors as William H. Macy and Delroy Lindo may not add much to the overall narrative, but they certainly seem to be having a ball.) Such deviations can't entirely alter the basic bedrock conventions of the formula, but it helps to maintain a welcome lightness mostly alien to the majority of the modern action behemoths.

On the other side of the camera, things are slightly less inspired, yet still more than serviceable. Debuting director Breck Eisner (son of Disney head honcho Michael) may lack the crackerjack pizzazz of a Cameron or Spielberg, but his action scenes feature a coherence often missing in the Bruckheimer age of films; shockingly, it is often possible to tell where characters are in relation to each other and who's shooting at whom. A constant supply of '70s fuzz-rock staples flood the soundtrack, and further enhance the overall resin-tinged feeling.

Ultimately, the film's act of mild stoner genre subversion may never blossom into, say, what The Big Lebowski did to the detective story, yet the muzzy-headed playfulness makes the copious testosterone heroics much easier to keep down. By the time a solar-powered secret base straight from the 007 vault makes an appearance, it's difficult to hold back the grins. (A feeling which apparently extended to the cast: The awesomely spacey indie staple Steve Zahn, until now best known for his indelible pothead in Soderbergh's Out of Sight, came to town recently and went on at exhaustive length at how jazzed he was to be allowed to ride camels and shoot machine guns in a major motion picture. Boy, does his enthusiasm ever show.) For a solid 127 minutes (7620 seconds), Sahara serves up a more-or-less constant buzz of mightily agreeable foolishness. Someone should turn it into a book.