This book investigates the anomalous magnetic field of the ocean and its connection with geological structure, tectonic evolution of the oceanic lithosphere, and magnetic properties of different rock types in the oceanic crust. The book describes new instruments and techniques of gradient magnetic measurements with three sensors, as well as the new technique of processing and interpretating hydromagnetic data on the basis of adoptive filtration and reparametrization. The text provides unique data of geomagnetic surveys carried out by Russian research vessels in different regions of the World...