Three words: Great Barrier Reef. Even if you've never dived, it's the one scuba-centric place in the world you're apt to know about. And with good reason: This reef off Australia is so massive that it is the only living underwater organism viewable from outer space.
Why do scuba divers name Australia's Great Barrier Reef one of their must-dives on their bucket list? The GBR is the largest and most extensive reef system in the world, stretching 1429 miles along the east coast of Australia and covering an area of more than 134,000 square miles. That's a whole lotta reef to explore.