Just about every sport today seems to have its extreme dimension. Among the wet and wild daredevils who surf for the cameras in Step Into Liquid are some intensely balanced souls who pursue waves off the coast of Hawaii so gigantic that the only way to approach the crashing walls of water is to get towed into them by motorboat. Even from the safety of a movie seat, you can just about feel the stinging hardness of the surf. Blue crush? This is more like white smash.
''Step Into Liquid'' is a great title for a surfing documentary, and the movie, written, edited, and directed by Dana Brown, lives up to that trippy sensual promise. Like his father, Bruce Brown, who made the ''Endless Summer'' movies, Dana Brown profiles surfers from all over the globe. He travels from the lush island settings of Maui and Rapa Nui to the cooler shoals of Ireland to such eccentric surf meccas as a Texas coast where the surfers rely entirely on waves created by oil tankers. At times, the amiable Zen grooviness of it all grows a bit monotonous, but, like the surfers themselves, you get addicted to those waves, especially the gorgeous pipeline curls that were featured in ''Blue Crush.'' If anything, ''Step Into Liquid'' underscores how accurately that movie captured the rush -- though in this case it all happens without digital enhancement. The closest the film comes to a special effect is Taj Burrow, a champion Australian surfer who whips up and down, like a banzai skateboarder, along the waves' curling crests. He may be the first surfer to fly out of liquid as effortlessly as he steps into it.