The opening of new port by the Brazilian Vale Inco nickel company is the impetus for an international operation to clear New Caledonian waters of hundreds of wartime mines.
Naval experts from France, the United States, Australia and New Zealand have joined the operation, dubbed Lagoon Minex, which is targetting the sea lanes to Noumea and Prony Bay.
The estimated 1,600 mines remaining from almost 1,900 thought to have been planted in the lagoon during the Second World War to ward off a possible Japanese invasion, each contains up to 300 kilogrammes of explosives or enough to sink a ship.
Our correspondent in Noumea, Claudine Wery, says Lagoon Minex will work around Noumea.
"On the surface there is no risk but in case of handling or in case of collision it could be, and in the Prony Bay where Brazilian giant Vale Inco is building the big nickel plant in there, there is a port and they will have alot of maritime traffic and that's why this area was a priority for this operation."
Claudine Wery says most of the mines are being "drowned" in deeper water well away from World Heritage sites.