Marine controlled-source electromagnetic (CSEM) sounding is a new tool available to geophysicists for offshore hydrocarbon exploration. Although the technique has been developed for the detection of deep hydrocarbon reservoirs with relatively high resistivities, it also has the potential to be a useful tool for geohazard mitigation via gas hydrate detection. The hydrate target occurs in the shallow section (hundreds of meters in depth), and is manifested by subtle resistivity contrasts (a few Omega -m). This requires modifications to the CSEM technique to extend its capability of imaging the shallower hydrate section.