New Caledonia archipelago is located in the South West Pacific between Australia and the Vanuatu archipelago. The land covers 19,100 km2, and the EEZ and territorial waters extend to 1,450,000 km2. The main island, Grande Terre, is surrounded by a barrier reef of 1100 km length enclosing a large lagoon of 24,000 km2 and up to 60 m deep. The complexity of the maritime environment is controlled by both the westward South Equatorial Current and the border currents induced by its deflection against the islands. The climate is driven by the South Pacific Convergence Zone and fluctuates with ENSO events. Although rare, cyclones are a significant climatic risk in the country. Shallow coastal habitats consist of rich and diverse coral reef habitats and associated ecosystems including mangrove forests, seagrass meadows, macroalgal beds, and lagoonal soft bottoms which house tens of thousands of species. New Caledonia has low population densities (15 km− 2) and small urbanized areas. Most of the people live on the coast with two-thirds in the Greater Nouméa area. Despite the relatively low anthropogenic pressure on marine ecosystems, the development of mining industries is driving a range of environmental impacts and their associated ecological consequences. Subsidence fishing and agricultural activities are traditionally important for rural people. However, practices have changed considerably with the development of recreational fishing and with offshore fisheries with industrial long-lining. After attempts at seafood aquaculture (shrimps, oysters), a recent diversification is toward high-value marine resources (sea cucumber, microalgae). Maritime traffic including the cruise tourism industry has expanded by 10% over recent decades, requiring improvements of port infrastructure. Numerous regulations have been enacted for protection and conservation of marine species, areas, and habitats under the responsibility of provincial and government authorities. Two significant steps have been taken with the inscription in the World Heritage listing of half of the reefs and lagoonal areas and the creation of the Coral Sea Natural Park that represents 78% of France’s MPAs. This should help in maintaining the good environmental condition of the maritime areas of New Caledonia.