We develop a complete set of algorithms to perform 3D modelling of seamount bathymery from satellite altimetry. The first stage of the data processing consists in gridding the geoid: to account for the long wavelength errors geoid heigths are first bias-adjusted at cross-overs. Then a collocation on a regular grid is performed, accounting for the alimeter errors. In a second stage, geoid height are converted into bathymetry. No simplifying assumption on the location shape and location of the bathymetry highs is necessary. Bathymetric uncertainties due to the data sampling and the parameters of the mechanical and crustal models are evaluated. ¿American Geophysical Union 1991