Six Greenpeace activists board a coal ship bound for South Korea near Australia’s Great Barrier Reef in this handout picture from environmental group Greenpeace

Six Greenpeace activists board a coal ship bound for South Korea near Australia’s Great Barrier Reef in this handout picture from environmental group Greenpeace April 24, 2013. The group were protesting against the expansion of the rich Australian coal industry and its impact on the World Heritage site. Environmentalists say the Great Barrier Reef, a popular tourist site worth about A$6 billion ($6.1 billion) a year to the Australia economy, is threatened by dredging, sedimentation and coal port and shipping development. UNESCO will decide in June whether the reef should be listed as a World Heritage Site in danger. REUTERS/Greenpeace/Handout (AUSTRALIA – Tags: CIVIL UNREST ENVIRONMENT) ATTENTION EDITORS – NO SALES. NO ARCHIVES. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS