A good IMAX film usually combines eye-popping visuals with a "teachable moment," a little history, geology, biology or what not, tucked in between the pretty pictures. Grand Canyon Adventure, opening Saturday at the Orlando Science Center, more than fills that bill as an entertaining kayak's-eye-view of the gorge. And if we learn why the Spaniards might not call it the Rio Colorado ("color red") today because of drought and man-made interference with the river that runs through it, that's a bonus.

MacGillvray Freeman Films, who did Everest and Hurricane on the Bayou, take their cameras over, onto and under the Colorado, up the sides of the canyon, capturing it in all its rapids-running glory. And since this raft and kayak trip features an anthropologist (Wade Davis) and a river keeper (Robert F. Kennedy Jr.), we learn how Las Vegas and Southwestern farming are draining the river, how dams are lowering the water temperature and removing needed sediment and how the lakes behind those dams are evaporating away the precious water.

Robert Redford narrates, the teenage daughters of Davis and Kennedy frolic in swimsuits, and we see, from old photographs compared to the new, how the river isn't what it used to be, and learn how we ought to care about saving this "river at risk."