The use of controlled source electromagnetics (CSEM) in the marine environment has grown rapidly in the past few years from a simple anomaly fluid-hunting technique used in geologically simple environments to a modeling and inversion based technique applied in structurally and lithologically complex environments (Carazzone et al., 2005). The tool set most commonly available to interpreters includes one-, twoand three-dimensional forward and inverse modeling codes. All previous examples, reported in the literature, of inversion codes applied to marine CSEM data have been cell-based regularized techniques designed to produce the smoothest possible isotropic conductivity model (in twoor three-dimensions) which fits the observed data. We report on the development of a new technique, anisotropic sharp-boundary inversion in which the model is parameterized by two-dimensional interfaces. In this approach anisotropic conductivity can have sharp contrasts across interfaces. Regularization is applied to the smoothness of the interface and the lateral variations of conductivity between interfaces. We demonstrate a work flow that progresses from forward modeling through fast depth migration to smooth cell based inversion, concluding with sharp boundary inversion for the final interpreted conductivity image.