Stacy Peralta gives the Hollywood term "triple threat" a whole new meaning. The skateboarder/surfer/director turns in his second accomplished documentary in three years with Riding Giants, a follow-up to his critical darling Dogtown and Z-Boys. One might consider Peralta the film industry's chief chronicler of extreme sports, if that didn't belittle how seriously he takes his craft. As with Dogtown, Peralta has really done his homework, unearthing yards of priceless footage of 1950s big-wave surfers and their wonky postures. During this era of the film, he also identifies surfing as the centerpiece of a new counterculture, consisting of beach bums with no prospects other than to gleefully anticipate the swells. Where Giants diverges from Dogtown is that it pushes the sport's societal impact to the background, opting for a more mechanical focus on new techniques and the defiant quest for ever more bone-crunching waves. This turns the film into more of a highlight reel than a historical tableau. The problem is that, lacking the panoramic perspective of standing on the beach, most viewers have a difficult time appreciating the increasing enormity of the waves down through the decades. The feats are quite impressive, but the interview subjects' array of superlatives grows a tad repetitive. For the most part, though, it's a thrilling and entertaining window into a world of athletes who take as many risks with their lives as mountain climbers. Especially cool are the interviews with big wave godfather Greg Noll, who paved the waves at Hawaii's Waimea Bay. He recalls the era with off-color observations and a youthful bravado that belies his stocky, nearly 70-year-old body.