Potential field anomalies of the Sea of Okhotsk region are analyzed for compiling a map of the basement's tectonic structures. A 3D density model of the Earth's crust is constructed using seismogeological and experimental-petrophysical data, which made it possible to obtain a visual image of main structures of the region reflecting the observable geophysical anomalies. The obtained data allow a domain located in the central part of the Sea of Okhotsk beyond the limits of the exclusive economic zone of the Russian Federation to be considered as a natural continuation of the continental shelf since the latter is structurally similar to western Kamchatka. The deep structural boundaries rise beneath the large sedimentary Deryugin and Tinro basins, which is characteristic of petroliferous basins.