The Great Barrier Reef attracts over 2,000,000 million visitors a year and is a massive natural resource because of the amount of money it brings in from tourism. The reef also holds a significant amount of biodiversity and to damage the reef hurts the species of marine life that live there. The Great Barrier Reef has been declining over the years and recently the Australian government is planning to build a massive expansion of a coal port near the reef. The expansion of this coal port could prove to be the tipping point for the Great Barrier Reef. There are many different factors that have been effecting the reef over the years mainly climate change and overfishing. The port would bring an estimated 28,000 jobs, but also would dump dredged material into coastal areas that could affect the reef.
This Washington Post article gives more details.