The Great Barrier Reef in Australia is probably the most well known natural wonder of the world. "World Heritage" listed in 1981, it's a truly magnificent marine wilderness and nature reserve, unlike anything else, anywhere else.  The Barrier Reef is actually a series of 2100 individual reefs stretching for more than 2300 kilometers, from Papua New Guinea in the north down the Queensland coast to Lady Elliott Island (400 kilometers north of Brisbane, the capital of Queensland).  In addition to the reefs, there are some 500 islands, once part of the mainland until the oceans rose tens of thousands of years ago. The Great Barrier Reef is home to over 400 species of coral, 1500 species of fish, 4000 species of mollusc, 500 species of seaweed and 200 species of birds.  There are numerous ways to explore this amazing place, from aircraft flyovers to helicopter trips to sailing boats to the general tourist-type, look-see trips.  But the only way to really experience this wonderland is first-hand, underwater.  If you think you've been diving in some amazing places in the world, as the saying goes, "You ain’t seen nothing yet!"