This paper describes an effort to adapt a fleet of autonomous underwater vehicles (AUVs) for the measurement of the magnetic signature of surface ships. Currently, two such vehicles have been upgraded with the necessary navigation and measurement hardware to perform magnetic measurements. Initial testing has been performed at the Naval Acoustic Research Detachment at Lake Pend Oreille, Idaho. Two vehicles have leveraged formation control algorithms originally developed for mine countermeasure missions to operate collaboratively. In the testing area, changes in ambient field were measured to be ∼1,000-2,000 nT. Over one square meter area segments, the standard deviation of total field measurements was below 25 nT. When a steel barge was located in the testing area, localized fields of ∼50,000 nT to ∼62,000 nT were observed.