The employed method of 3D gravity modeling is based on calculation of the gravity effects of the main density boundaries of the lithosphere, subtraction of these effects from the observed gravity field, and the subsequent conversion of the residual gravity anomalies first to the Moho depth and then to the total thickness of the Earth's crust and the thickness of its consolidated part. On the modeling, we also took into account the gravity effects due to an increase in the sediment density with increasing sediment depth and a rise of the top of the asthenosphere beneath the mid-ocean Gakkel Ridge. The resulting 3D models of the Moho topography and crustal thickness are well consistent with the data of deep seismic investigations. They confirm the significant differences in crustal structure between the Eurasian and Amerasian Basins and give an idea of the regional variations in crustal thickness beneath the major ridges and basins of the Arctic Ocean.