The paper contains the results of combine studying of the Sea of Okhotsk continental margin. The structure of its surface, modern geodynamics, geophysical parameters and deep structure are investigated. Potential field anomalies of the Sea of Okhotsk have been analyzed. The 3D density model of the main Earth crust structures is compiled and calculated, leaning on the seismic-geological and experimental petrophysical data. The model gives a visual explanation for the observed geophysical anomalies. The schematic map of the basement tectonics is one of the investigation results. So we come nearer to the solution of the general regional problems of the Earth crust construction and the exploration prospects. Analysis of the received geophysical material helps to improve the planning of the future projects and allows to determine the Sea of Okhotsk enclave area locating outside the exclusive economic zone of the Russian Federation as the natural continuation of continental margin.