Seafloor subsidence effects due to cooling of the oceanic lithosphere have been removed from bathymetry data. The corrected ocean floor topography presents long wavelength highs, in particular over western Pacific. We show in this study that this long wavelength residual topography can be interpreted as either a term of seafloor flattening at old ages or a dynamic response to large scale convection. Whatever its origin, this long wavelength residual topography is dominated by a degree 2 pattern highly correlated with geoid, lower mantle heterogeneities and plate age. ¿American Geophysical Union 1991