Watch Secrets of the Great Barrier Reef (2010) : Full Movie Online Free Down Under, just a few nights after the November full moon - when water temperature and tides are just right - one of nature's most extraordinary events explodes into life. Thousands of coral join in an elaborate mating ritual, a synchronized dance of naturally occurring phenomena that help increase the coral's odds of survival. Journey through more than 1,200 miles of Australia's treasured Great Barrier Reef to discover the secrets of the unique marine life that inhabit this dazzling spectacle, considered to be the world's biggest single structure made by living organisms and declared a World Heritage Site by UNESCO.