<p>The article considers a possibility of using electrical resistivity tomography to assist the engineering and geological surveys conducted within coastal sea waters. The efficiency of electrical resistivity tomography in aquatic and seafloor modifications for investigating the structure of coastal territories of freshwater and sea water areas is estimated. Basic geoelectrical and electrical resistivity tomography models of bottom sandy clay sediments with different water mineralization are synthesized. The influence of seafloor geomorphology within the coastal zone on electrical resistivity of dispersed soils is analysed. The pattern of the influence of pore water mineralization, temperature and clay mineral content on geoelectrical structure of dispersed rocks is ascertained. The results of computer modelling of electrical resistivity tomography sections made it possible to substantiate the advantages of ocean bottom electrical resistivity tomography for studying the geological structure of marine coastal territories. The results of experimental electrical resistivity tomography are presented confirming the efficiency of using electrical resistivity tomography to investigate the geological structure of coastal areas in the Sea of Okhotsk and Black Sea sections.</p>