Habitat degradation, fragmentation, and destruction are today the leading causes of species extinction on Earth. A major challenge for environmental managers, hence, is to e¿ciently balance land use between economic development and conservation of natural habitats. In New Caledonia, the smallest biodiversity hotspot in the world, ¿nding this trade-o¿ is tedious. In particular, the conservation of its highly diverse forest ecosystems, distinguished by high rates of endemism, can be con¿icting with mining activity, the major economic sector of New Caledonia. Managers are willing to study how to re¿ne decisional processes through the use of systematic conservation planning and computational sustainability. To this end, we considered the project ”Côte Oubliée” started in 2016 by the environ-mental managers of the South Province of New Caledonia. It aims at delineating a complex reserve system (including about 1200 km2 of terrestrial and 950 km2 of marine reserve) in the southeast of New Caledonia in an area with rich biodiversity and overlapping with di¿erent socioeconomic interests (such as 238 mining concessions, private and cultural lands, and ¿sheries) as well as 135 km2 of area to be restored. Our objective was to identify how the reserve could be e¿ciently delineated while respecting socioeconomic constraints. More precisely, we focused on the biodiversity representation as much as on the spatial con¿guration of the reserve. Additionally, we aimed at reducing fragmentation through the identi¿cation of areas suitable for ecological restoration. Relying on a constraint-based reserve selection model, we iteratively considered operational scenarios and produced maps providing the basis for decision support. The model was then re¿ned according to a feedback loop between managers and scientists. Through this iterative process, we could suggest a delineation of the reserve that maximized the representation of biodiversity features while satisfying managers constraints. W