Activists in New Caledonia say they are happy that its reefs and lagoon have been made a Unesco World Heritage Site.
The decision to recognise 15,000 square kilometres of the world's second largest coral reef has been made at a Unesco meeting in Canada.
The zone includes a lagoon in the south, where activists have campaigned against a Goro Nickel company waste pipeline, saying it will contaminate the area.
An environmental activist, Mike Hosken, has welcomed the announcement.
"I'm pleased but I'm a little bit sceptical about the classification in that we have a pipeline, which is half built at the moment, which is going to be filling industrial effluent out into one of the sites. This is incompatible to a world heritage authority site, and I'm not sure how they are going to work on that one."
Mike Hosken hopes the Unesco will call for a stop of the multi-million dollar nickel project.