As the world’s largest reef system, the Great Barrier Reef off the coast of Queensland, Australia, is one of the best scuba diving destinations in the world. Stretching roughly 1400 miles along Australia’s northeast coast, the Great Barrier Reef covers an immense area of more than 134,000-square miles. In fact, the coral that makes up its primary foundation is the Earth’s largest living structure — so large it can even be seen from outer space! Extending over such a vast expanse of ocean, the Great Barrier Reef is teeming with all manner of marine life, ranging from huge humpback whales to tiny clownfish. If you’re planning a dive vacation, Australia's Great Barrier Reef should definitely be at the top of your list.