The Great Barrier Reef is on the northeast coast of Australia. It is a UNESCO World Heritage Site.

The Great Barrier Reef is the world's largest coral reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,300 kilometres (1,400 mi) over an area of approximately 344,400 square kilometres (133,000 sq mi). The reef is located in the Coral Sea, off the coast of Queensland, Australia.

It also happens to be the largest single structure made by living organisms on our planet. Unfortunately, coral bleaching, probably due to climate change, threatens the reef and it's marine life. It's a destination vacation that you will love if you enjoy the ocean like I do. A dive boat will take you out to the reef and loan you everything you need to snorkel, or scuba dive to see the wonders under the water.

More Info: en.wikipedia.org