     the great barrier reef is the world's largest coral reef system composed of over 2,900 individual reefsthe great barrier reef world heritage area, which is 348,000&nbsp;km squared, has 2900 reefs. however, this does not include the reefs found in the torres strait, which has an estimated area of 37,000&nbsp;km squared and with a possible 750 reefs and shoals. (hopley, p. 1) and 900 islands stretching for over  over an area of approximately . the reef is located in the coral sea, off the coast of queensland, australia. the great barrier reef can be seen from outer space and is the world's biggest single structure made by living organisms. this reef structure is composed of and built by billions of tiny organisms, known as coral polyps.{{cite news |url=http
Australian_National_Heritage_List Coral_Sea Great_Barrier_Reef Marine_ecoregions Physiographic_provinces Reefs_of_Australia Underwater_diving_sites_in_Australia Visitor_attractions_in_Queensland World_Heritage_Sites_in_Australia