Direct current (DC) resistivity methods applied to geological mapping in marine environments can be very limited to shallow waters, depending on the resistivity contrast between seawater and the subsurface formations. In this paper, we introduce a new acquisition technique for increasing the signal sensitivity to geological targets, despite the presence of a seawater column. The suggested technique consists in the use of an insulating sheet laid directly on the electrode cable placed on the seafloor, an idea that had been previously patented. As a first step in assessing the efficiency of this approach, a synthetic study was carried out. Results are presented and briefly discussed. It is demonstrated that the increase in geoelectrical response sensitivity can be significant.