No map of the sea floor is available yet on the whole lagoon of New Caledonia. We tried to validate a method to map it with MeRIS images on the south western part of the lagoon. The non-linear effect of water column light attenuation can then be corrected to obtain the absolute reflectance of the seabed. Light attenuation by the water column can be determined by comparing the radiance of standard features on the seabed at different depth. Bathymetry can also be determined by measuring the relative reflectance of the seabed in green and red light spectral bands. Once the effect of attenuation has been removed, a supervised classification can be applied in order to obtain the location of each item on the sea floor. Validations are operated with ground measurements of depth, spectral profiles and some available maps.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.