Four principal ecosystems exist in New Caledonia, the mangrove, savannas, the maquis and the forest. The flora of these ecosystems includes 3500 species, of which 75 % are endemic, however the known fauna includes a thousand of fish, 6500 types of molluscs and 4300 species terrestrial, among which the famous cagou, terrestrial bird used as an emblem of New Caledonia.

The marine environment owes its richness to the presence of a coral reef barrier surrounding New Caledonia, and whose distance from to the coast can reach 65 km: it delimits the largest and most beautiful closed lagoon of the world with its 24 000 Km² of turquoise water and a depth of 40 Mr maximum.  Marine reserves were created in order to safeguard this diversity, which because of the low density of the population and the activities, is still preserved.