Starring Seth Green, Matthew Lillard, and Dax Shepard. Rated PG.

From the ads, you'd fully expect Without a Paddle to be a dumb-ass teen comedy. And you'd be right. But it's also sweet and oddly heartening, in its own dumb-ass way.

Buddies Dan (Seth Green, at his smallest), Jerry (Matthew Lillard, a little less shaggy than usual), and Tom (Punk'd veteran Dax Shepard, stepping into his big-screen career) have grown up to be less than they were supposed to be. After this surprisingly melancholy opening, the death of a fourth pal--the most successful of the gang--inspires them to take one more chance to do something stupid together, in the form of a long-gestating search for the buried treasure of fabled airline hijacker D. B. Cooper.

The impromptu trip takes them to deepest Oregon, which, shockingly, is not portrayed by British Columbia but by the nation of New Zealand. Instead of magic rings, they encounter whitewater mishaps, an ornery sheriff, hairy-legged tree huggers, '80s references up the wazoo (not the river they're rafting on, by the way), and more homophobia than you can shake a--hey, just shake anything at it, okay?

The film is handled in a surprisingly relaxed manner--considering the pileup of the scenes with crazed, gun-wielding pot farmers--by Steven Brill, an actor turned writer and director previously responsible for such probing fare as Little Nicky and the Mighty Ducks movies. The script, credited to five other guys (all actor-writers, including Canadian Harris Goldberg), is piecemeal stuff, but some of the pieces are smartly turned and the actors (especially Shepard, who's like a cranky, old geezer in a young man's body) are perfectly suited to its good-natured rhythms. Even the sexual panic that runs through the movie seems to be a mere ritual for them to riff on.

As far as the support work here, let's just say that the notion of Burt Reynolds as a character actor is advanced by his cameo as a codger who could have crawled out of Deliverance. This time around, he's in a position to make the city slickers squeal like a pig.