The Great Barrier Reef is massive. Its ecosystem of 3,000 individual coral reefs stretches a whopping 2,300 kilometers (1,430 miles), or roughly the distance from Vancouver to the border of Mexico, and covers an area of 344,400 square kilometers (133,000 square miles). It's so big, in fact, that it can be seen from outer space. According to the Australian government's Great Barrier Reef Marine Park Authority, the Reef is home to a dazzling array of creatures, including 3,000 varieties of mollusks, more than 100 types of jellyfish, 1,625 species of fish, 133 types of sharks and rays, and more than 30 species of whales and dolphins. That's in addition to the many types of soft and hard corals that form the area's 30 distinct bioregions, each of which are made up of different types of reefs.
With all this biodiversity, it's understandable that the Great Barrier Reef would need protecting. Tourism, pollution, and agricultural runoff pose hazards to the Reef's fragile ecosystem, but climate change is its most serious threat, according to the Great Barrier Reef Marine Park Authority's 2014 Outlook Report. Rising sea temperatures can lead to coral bleaching, and the gradual acidification of the oceans can stunt coral growth. But while the Great Barrier Reef is in danger, scientists say that it's not too late to save it. Learn more about this massive natural structure with the videos below.