The Great Barrier Reef, the immense coral reef system covering an area more than 133,000 square miles off the north-east coast of Australia, is the largest structure formed by living organisms on the planet.
The Great Barrier Reef is a UNESCO World Heritage Site and is home to 600 types of corals and over 1,600 types of fish.
Though the Great Barrier Reef has lost around half its coral cover in the last 30 years, the world heritage committee declined to list it as "endangered" on July 1, 2015. The committee did express concern regarding the reef's decline and the need for it to be vigorously protected, essentially putting Australia on probation with the status to be reviewed in the future. UNESCO called the reef's outlook earlier in the year "poor."
The UNESCO delegates snorkeled the reef as part of their mission to verify the health of the world's largest living ecosystem, which brings in billions of dollars a year in tourism for Australia.
Here, Lady Elliot Island located north-east of the town of Bundaberg in Queensland, Australia, is seen on June 11, 2015.