Sediment can be seen in the water as ships and boats sail past the coastal town of Hervey Bay, north of Brisbane in Queensland, Australia, June 9, 2015. UNESCO World Heritage delegates recently snorkelled on Australia’s Great Barrier Reef, thousands of coral reefs, which stretch over 2,000 km off the northeast coast. REUTERS/David Gray 

Homes can be seen along a creek and inlet in the coastal town of Hervey Bay, north of Brisbane in Queensland, Australia, June 9, 2015. UNESCO World Heritage delegates recently snorkelled on Australia’s Great Barrier Reef, thousands of coral reefs, which stretch over 2,000 km off the northeast coast. Surrounded by manta rays, dolphins and reef sharks, their mission was to check the health of the world's largest living ecosystem, which brings in billions of dollars a year in tourism. Some coral has been badly damaged and animal species, including dugong and large green turtles, are threatened. UNESCO will say on Wednesday whether it will place the reef on a list of endangered World Heritage sites, a move the Australian government wants to avoid at all costs, having lobbied hard overseas. Earlier this year, UNESCO said the reef's outlook was "poor". REUTERS/David Gray TPX IMAGES OF THE DAY

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Pilot John Peaker prepares to land on Lady Elliot Island located north-east of the town of Bundaberg in Queensland, Australia, June 9, 2015. Some coral has been badly damaged and animal species, including dugong and large green turtles, are threatened. REUTERS/David Gray 

An aerial view of Lady Elliot Island located north-east of the town of Bundaberg in Queensland, Australia, June 11, 2015. UNESCO will say on Wednesday whether it will place the reef on a list of endangered World Heritage sites, a move the Australian government wants to avoid at all costs, having lobbied hard overseas. REUTERS/David Gray 

Tourists walk from a boat after diving in an area called the 'Coral Gardens' located at Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 9, 2015. Earlier this year, UNESCO said the reef's outlook was "poor". REUTERS/David Gray 

Tourists prepare to board a boat to snorkel in an area called the 'Coral Gardens' located at Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 10, 2015. REUTERS/David Gray 

A boat carrying tourists floats above an area called the 'Coral Gardens' near Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 10, 2015. UNESCO World Heritage delegates recently snorkelled on Australia’s Great Barrier Reef, thousands of coral reefs, which stretch over 2,000 km off the northeast coast. Surrounded by manta rays, dolphins and reef sharks, their mission was to check the health of the world's largest living ecosystem, which brings in billions of dollars a year in tourism. Some coral has been badly damaged and animal species, including dugong and large green turtles, are threatened. UNESCO will say on Wednesday whether it will place the reef on a list of endangered World Heritage sites, a move the Australian government wants to avoid at all costs, having lobbied hard overseas. Earlier this year, UNESCO said the reef's outlook was "poor". REUTERS/David Gray

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Tourists look through a glass window in the bottom of a boat as it floats above an area called the 'Coral Gardens' located at Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 10, 2015. REUTERS/David Gray 

Tourists snorkel near a turtle as it looks for food amongst the coral in the lagoon at Lady Elliot Island north-east of the town of Bundaberg in Queensland, Australia, June 9, 2015. The lagoon, which is occupied by turtles during high tide, is only accessible for snorkelling during this time. REUTERS/David Gray 

Peter Gash (L), owner and manager of the Lady Elliot Island Eco Resort, snorkels with Oliver Lanyon and Lewis Marshall, senior rangers in the Great Barrier Reef region for the Queenlsand Parks and Wildlife Service, at Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 11, 2015. They are carrying out an inspection of the reef's condition in an area called the 'Coral Gardens'. Gash snorkels every morning before he attends to managing duties on the island, and was showing the Great Barrier Reef rangers the current condition of the reef. REUTERS/David Gray 

Peter Gash, owner and manager of the Lady Elliot Island Eco Resort, snorkels during an inspection of the reef's condition in an area called the 'Coral Gardens' located at Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 11, 2015. Gash snorkels every morning before he attends to managing duties on the island, and was this morning showing the Great Barrier Reef rangers the current condition of the reef. REUTERS/David Gray 

A tourist snorkels in an area called the 'Coral Gardens' located at Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 10, 2015. REUTERS/David Gray 

Tourists stand in front of huts that form part of the Lady Elliot Island Eco Resort where a turtle digs for food amongst the coral in the island's lagoon, north-east of the town of Bundaberg in Queensland, Australia, June 9, 2015. REUTERS/David Gray 

Peter Gash, owner and manager of the Lady Elliot Island Eco Resort, prepares to snorkel during an inspection of the reef's condition in an area called the 'Coral Gardens' located at Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 11, 2015. Gash snorkels every morning before he attends to managing duties on the island. REUTERS/David Gray 

A tourist snorkels in the lagoon located on Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 9, 2015. The lagoon, which is occupied by turtles during high tide, is only accessible for snorkelling during this time. REUTERS/David Gray 

Dried coral and shells lie on a beach on Lady Elliot Island, north-east of the town of Bundaberg in Queensland, Australia, June 10, 2015. REUTERS/David Gray 

Small bushes grow on a coral beach on Lady Elliot Island located north-east of the town of Bundaberg in Queensland, Australia, June 9, 2015. UNESCO World Heritage delegates recently snorkelled on Australia’s Great Barrier Reef, thousands of coral reefs, which stretch over 2,000 km off the northeast coast. Surrounded by manta rays, dolphins and reef sharks, their mission was to check the health of the world's largest living ecosystem, which brings in billions of dollars a year in tourism. Some coral has been badly damaged and animal species, including dugong and large green turtles, are threatened. UNESCO will say on Wednesday whether it will place the reef on a list of endangered World Heritage sites, a move the Australian government wants to avoid at all costs, having lobbied hard overseas. Earlier this year, UNESCO said the reef's outlook was "poor". REUTERS/David Gray

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A reef shell lies on a beach as the sun sets on Lady Elliot Island located north-east of the town of Bundaberg in Queensland, Australia, June 10, 2015. REUTERS/David Gray 

The Milky Way is seen in the sky above a path and huts on Lady Elliot Island located north-east of the town of Bundaberg in Queensland, Australia, June 10, 2015. UNESCO World Heritage delegates recently snorkelled on Australia’s Great Barrier Reef, thousands of coral reefs, which stretch over 2,000 km off the northeast coast. Surrounded by manta rays, dolphins and reef sharks, their mission was to check the health of the world's largest living ecosystem, which brings in billions of dollars a year in tourism. Some coral has been badly damaged and animal species, including dugong and large green turtles, are threatened. UNESCO will say on Wednesday whether it will place the reef on a list of endangered World Heritage sites, a move the Australian government wants to avoid at all costs, having lobbied hard overseas. Earlier this year, UNESCO said the reef's outlook was "poor". REUTERS/David Gray

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Storm clouds can be seen above a coal ship as it sails near Lady Elliot Island located north-east of the town of Bundaberg in Queensland, Australia, June 9, 2015. UNESCO World Heritage delegates recently snorkelled on Australia’s Great Barrier Reef, thousands of coral reefs, which stretch over 2,000 km off the northeast coast. Surrounded by manta rays, dolphins and reef sharks, their mission was to check the health of the world's largest living ecosystem, which brings in billions of dollars a year in tourism. Some coral has been badly damaged and animal species, including dugong and large green turtles, are threatened. UNESCO will say on Wednesday whether it will place the reef on a list of endangered World Heritage sites, a move the Australian government wants to avoid at all costs, having lobbied hard overseas. Earlier this year, UNESCO said the reef's outlook was "poor". REUTERS/David Gray

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A ship is loaded with coal at the RG Tanna Coal Terminal located at the town of Gladstone in Queensland, Australia, June 12, 2015. REUTERS/David Gray 

A pile of processed metal sits near the Barney Point shipping port located in the town of Gladstone in Queensland, Australia, June 12, 2015. REUTERS/David Gray 

Port workers load a ship with coal at the RG Tanna Coal Terminal located at the town of Gladstone in Queensland, Australia, June 12, 2015. REUTERS/David Gray