The primary objective is to categorically determine the technical feasibility of the thermally, acoustically and optically compensated, ultra-low-noise, "all-passive" miniaturized fiber-optic magnetic sensor. Supporting objectives are: 1) characterization of the magnetic sensor's operational environment; 2) definition of the preliminary system requirements; 3) assessment of components, subsystems and system; 4) evaluation of design margins through first-order modeling and analysis of miniaturized design embodying preferred concept and modified configurations; 5) estimation of practical design margins, and tolerances in achieving a stable magnetic sensor performance in the deep sea environment of 1 nanotesla. Edwards communications electro-optics in vienna, va with consultational assistance from MIT Prof. S Ezekiel, MIT Cambridge, MA evaluates technical feasibility of the innovative concept through first order modelling and analyzes of the compensated magnetic sensor system. The effort will address the project objectives individually in five interrelated subtasks.