**5. Conclusions**

The superspectral WorldView-3 providing 16 bands, from 400 to 2365 nm, pansharpened at 0.3 m, was acquired in the form of stereo-imagery. Both topographic and bathymetric DSMs were built using a handful of ground and sea control points, enabling us to calibrate/validate the land-based photogrammetry and the sea-based radiative transfer model, provided with 1.11 and 0.89 m vertical accuracy, respectively. The best superspectral combination for enhancing the land-sea mapping of 13 habitats relied on the merging of the optical dataset (VIS+NIR) and the MIR8, which enhanced the basic BGR classification accuracy by 9.58%, thus reaching an OA of 98.73%. The classes that most benefited from this were the land use "roof" and land cover "soil" classes. The "coral reefs" consisted of the sea class that was the most favoured. The addition of the satellite-derived topobathymetric DSM to the optical+MIR1 was the best full combination, increasing the basic BGR classification accuracy by 9.73%, thus reaching an OA of 98.88%. The discrimination of the "roof" and "soil" classes was also strengthened, but the "coral reefs" remained constant.

**Author Contributions:** Conceptualization, A.C. and M.A.; methodology, A.C., D.L. and J.C.; software, A.C. and M.A.; validation, A.C.; formal analysis, A.C.; investigation, A.C. and J.C.; resources, A.C. and M.A.; data curation, A.C. and M.A.; writing—original draft preparation, A.C.; writing—review and editing, A.C., M.A., D.L. and J.C.; visualization, A.C. and M.A.; supervision, A.C. and J.C.; project administration, A.C. and J.C.; funding acquisition, M.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was partly funded by the DigitalGlobe Foundation and the CNRS PEPS called "Reef I Were".

**Conflicts of Interest:** The authors declare no conflict of interest.
