In November 2012, Australia began protecting a huge swath of its ocean from overfishing and oil exploration, creating the largest network of marine reserves in the world at a grand total of 1.2 million square miles (3.1 million square kilometers). The area, a third of the continent’s territorial waters, includes an underwater canyon as large as the U.S. Grand Canyon, seagrass meadows, and the biodiverse reefs of the Coral Sea, including the one pictured here at Montague Island.