123Movies. Mysterious and only superficially explored by generations of the native Aborigines, Australia's Great Barrier Reef is one of the world's most extraordinary natural life systems. Twelve hundred miles long and made up of coral, it is the Earth's largest structure built by living things, in some places extending 120 miles into the sea. So many varieties of life call the reef home that more than a dozen species can be found within any square meter of its surface. This IMAX film brilliantly captures the visual splendor of this environment with splendid underwater photography typical of the format. Sharks, sea turtles, anemones, and the coral itself are the living subjects of the camera's probing eye. Overall, this documentary is a comprehensive look at this long-studied web of life that leaves a lasting impression of its depth and beauty.