The reef and lagoon in New Caledonia have been made a Unesco world heritage site.
The announcement has been made in Canada and comes just a day after Papua New Guinea's ancient Kuk agriculture site was made the Pacific Islands' first entry on the Unesco list.
The New Caledonian bid was for the world's second longest coral reef and the lagoon in the south where environmentalists have campaigned against effluent to be released from the Goro Nickel project.
15,000 square kilometres of the zone has now been recognised.
The vice-president of the New Caledonian Congress, Isabelle Ohlen, has welcomed the listing, saying it is the first of a site in France's overseas territories.
