Surface ship and submarine magnetic field signatures have been exploited for over 80 years by naval influence mines, and both underwater and airborne surveillance systems. In this book, author John Holmes presents the generating mechanism of the four major shipboard sources of magnetic fields, along with a detailed description of the induced and permanent ferromagnetic signature characteristics.Holmes presents a brief historical summary of magnetic naval mine development during World War II followed by a discussion of important improvements found in modern weapons, including an explanation of the damage mechanism for non-contact explosions. This is followed by a brief historical discussion of underwater and airborne submarine surveillance systems and magnetic field sensing principles, in which mathematical formulations are presented for computing expected target signal strengths and noise levels for several barrier types.Also outlined is a multi-layered defensive strategy against naval mines, with graphical explanations of the relationships between ship signature reduction and minefield clearing effectiveness. Equations for estimating geomagnetic, ocean surface wave, platform, and vector sensor motion noises are presented along with simple algorithms for their reduction.