Eight years ago, Bruce Brown began traveling through Southern California to show his 16mm surfing film, Slippery When Wet, to crowds of the initiated in high school auditoriums.

Brown's narration was corny--yet totally unselfconscious. The young California surfers in the featured roles mugged shamelessly, as people always do in home movies--but once they paddled their boards out to catch the fearsome winter waves, they were awesome.

And when they pulled themselves erect for the take-off, it was clear that Brown's film was about the sport of surfing, not the cult. He ignored the beach goings-on, the bikinied "beach bunnies," and the faked-up music; instead he kept his camera on the athletes who navigated through a sea of underwater rocks, stray boards, sharks, poisonous fish, and other surfers.

Since 1958, surfing has become so fashionable and so ubiquitous that New York hippies and Nebraska teenagers can talk convincingly about "wiping out" on the Newport Beach "Wedge." Singing groups have accumulated fortunes by exploiting tenuous attachments to the sport.

Brown's films, however, haven't changed much, although even the august New York critics felt moved to comment on his newest and first nationally distributed film, The Endless Summer. He produced, directed, filmed, narrated, and edited it himself, and it has all the spontaneity and informality of Slippery When Wet. He still makes home movies.

The Endless Summer is essentially a travelogue, with only the meagerest story line: Brown photographs two young surfers as they travel around the world, seeking the perfect wave and following the summer sun.

To the rational mind, this may seem to be an unlikely adventure, yet Brown, an expert surfer and a skillful camerman, manages to make it convincing. As in his four previous films, he offers a believable explanation of the surfers' dream world, where long waves break evenly on isolated beaches and the sun never sets.

He has an afficianado's knowledge of surfing hazards and an appreciation of the expert's skill and grace. His narration proceeds smoothly; he intersperses cracks about particularly bad wipeouts with wise asides about air and water temperatures, the incline of the continental shelves, and the price of gas in Ghana.

Although Brown shies away from sociological insights, he and the two young surfers sometimes seem to regard their journey around the African and Asian perimeters as part of the "white man's burden." Or perhaps they're just ingenuous innocents abroad. They bring surfing to the natives, tolerate the Africans' God-given clumsiness, and develop Moses complexes.

Brown relates that there was a "spooky silence" as the menacing Africans gathered along the beach, but then as the boys catch the first wave and stand up, the Africans burst into reverent shrieks and shouts. The noise frightens the surfers, who fear they have violated some "tribal taboo" and are about to be pursued by natives "carrying the biggest forks they'd ever seen."

Other incidents Brown relates--meetings with an African game hunter who milks cobras for a living and a cabdriver who insists the boards have to ride in the trunk--are genuinely amusing and sustain the film.

For eventually, looking at waves breaking on beaches, whether they are Senegalese or Tahitian, becomes tiresome. Like most amateur filmmakers, Brown doesn't know where to end The Endless Summer; he has to show just one more well-known surfing haunt and one more surfer bleeding from an ugly gash on the forehead. The ingenuous quips and noises eventually come to seem plainly adolescent.

But it is misleading to imply that more than a few moments of The Endless Summer are wavering or forced. The photography is superb, particularly those scenes actually filmed on a surfboard with a waterproof housing wrapped around the camera. And Brown's commentary, if you can stomach the occasional barbarisms or pass them off as charming naivete, is funny and quick.

What is best about The Endless Summer can be summed up by Brown's breathless statement after the boys find their perfect wave at some uninhabited spot on the Indian Ocean. "Just think," Brown muses. "Think of the thousands of waves that have gone to waste here."