Abstract: Cost-effective compact magnetometers can be deployed across large ocean areas to record magnetic field strengths. Each magnetometer has a canister containing a magnetometer sensor at its upper end to detect magnetic field strengths of magnetic influence sweep systems and provide representative data signals. Each magnetometer also has sensors to collect data representative of the orientation of the magnetometer as well as temperature and depth to aid in post operational evaluation of the gathered magnetic strength data. A computer processor connected to the sensors controls receipt of the data signals and stores them in a memory device. Batteries at the canister's lower end supply power for the sensors, processor, and memory. An anchor release mechanism causes an anchor to separate from the canister, allowing it to float to the surface for recovery or to transmit data via a UHF transceiver.