Many of the action shots are quite magnificent in this surfing documentary from Dana Brown, son of the filmmaker whose “Endless Summer” pictures (the 1966 original and the 1994 sequel) have taken on an almost mythic significance for devotees of the sport and those who merely look upon the search for “the perfect wave” as a metaphor for human dreaming and striving in the broadest sense. “Step Into Liquid” is a worthy addition to the canon; it shares with his father’s films both stunning visuals and often banal commentary. At its best exhilarating and at its worst repetitious and curiously preachy, it’s a mixed bag, but more diamond than zircon.

The point in “Liquid” isn’t so much to tell a story as to capture the common spirit in which surfers catch waves all over the world. Thus we’re treated to shots of Wisconsin enthusiasts watching for ride-worthy days on the Lake Michigan coast and Texas ones chasing oil tankers as they steam through the Galveston channel and send out waves in their wake, and a sequence centering on three American brothers braving the cold waters off the Irish coast, as well as scenes involving the more conventionally gorgeous sites in Hawaii and Tahiti. We’re also treated to episodes introducing innovative surfing techniques–like a journey a hundred miles off the California beach to ride huge swells churned up there.

But the film wants to be more than a travelogue; its aim is to show the almost mystically exuberant, joyous attitude that surfers share, wherever they are. The picture successfully counteracts the “surfer dude” caricature, alternately glory-seeking or slacker, that’s dominated over the years by offering instead portraits of the middle-class Sheboygan guys who have surfed together for years and the Malloy siblings, who invite Catholic and Protestant Irish youths to surf together as a small step toward reconciliation. And then there’s Dale Webster, a fellow who’s aiming to surf every day for thirty years straight–not for any special recognition, but out of sheer love of the experience, and Jesse Billauer, who continues to surf though an accident has partially paralyzed him. Pros, ranging from multiple champion Kelly Slater to up-and-coming Aussie Taj Burrows, and reporters add their observations, too, but they also emphasize the feeling of surfing, rather than their own accomplishments. In short, surfers are a special breed, Brown tells us, marked not by arrogance but by extraordinary comradeship and mutual respect, as well as the mysterious appeal of the waves.

To be sure, the message of “Step Into Liquid” does get a trifle heavy at times, despite Brown’s effort to restrain it with self-deprecatory humor, and there are moments when the narration takes on a hushed, almost homiletic tone. But the threat of pomposity is quickly dispelled by another shot of a surfer looking decidedly insignificant against the backdrop of some massive blue wall of water. Those breathtaking moments make the picture a mostly refreshing experience.