The coral reef that surrounds the French Pacific territory of New Caledonia is the second biggest in the world - after Australia's Great Barrier Reef.br br The reef is home to some of the world's most diverse marine life, and is a major source of food and income for locals.br br But it is coming under threat as the mining of nickel, another one of its richest natural resource, expands.br br Al Jazeera's Harry Fawcett reports from New Caledonia.