Admit it: Sometimes you get tired of art house movies starring actors who take "their craft" very, very seriously. Sometimes you want to buy an extra-large popcorn and settle in for a big budget Hollywood blockbuster replete with entertaining explosions, undemanding dialogue and completely unrealistic action sequences. If all that sounds like gloriously uncomplicated fun, "The Guardian" is your movie.

Ashton Kutcher, keeping his smirk to a bare minimum, plays Jake Fischer, a brash young Coast Guard recruit who's been selected to join the elite squad of rescue swimmers. Fischer, who has clearly studied the work of Tom Cruise in "Top Gun," shoots his mouth off at the first classroom session, only to be confronted by instructor Ben Randall (Kevin Costner), a legendary rescue swimmer who's carrying some serious psychic baggage.

Costner cuts down Kutcher with a decisiveness that would make Kelly McGillis proud. A lot of this movie calls to mind Tony Scott's 1986 tribute to the Navy's best fighter pilots, from Fischer's swagger and dark (putatively secret) history to Randall's refusal to let mediocrity taint his exclusive unit. "Top Gun" allusions aside, however, "The Guardian" stands solidly on its own in the action movie oeuvre, due primarily to the white-knuckle rescue sequences, filmed off the Oregon coast and in a meticulously constructed water tank.

Director Andy Davis, a Chicago native whose previous films include "The Fugitive," is clearly adept at staging and capturing the gripping adventures of men with something to prove. Kutcher, who admits having to brush up his swimming skills for the role of Fischer, has toned down his natural goofiness, emerging as a reasonably believable leading man. Costner's weathered, crinkled looks are useful here, as Randall squints meaningfully into raging rainstorms while contemplating the demise of his marriage to Helen (Sela Ward, saddled with perhaps the movie's most ridiculous line, delivered as she walks out on the inattentive Ben: "It's time for me to save myself").

There is something enormously refreshing about the Ward-Costner pairing; part of that is Ward's brisk, unsentimental delivery, but it's also to do with the age appropriateness of the couple. Unlike in so many male-dominated Hollywood films, the middle-age guy is still very much in love with his middle-age wife. (Granted, the middle-age wife looks like Sela Ward, but let's applaud progress where we can.)

We'll see whether "The Guardian" does for Coast Guard rescue swimming what "Top Gun" did for fighter pilots. Certainly the Coast Guard has never been considered the sexiest branch of the Armed Services, but this movie does a service showcasing the pure, selfless, occasionally foolhardy bravery of the swimmers who plunge into storm-lashed water to drag poor souls to safety. It also showcases the tooth-gnashing chauvinism and intermittent homophobia that seem to accompany any foray into masculinity.

Eventually, as you probably could have predicted, the movie descends into the sentimentality that haunts most of these "be all you can be" movies, but in between the maudlin moments, Davis et al. deliver a sturdy popcorn movie and a few genuine thrills. Not bad for a day on the high seas.