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A scalar magnetometer payload has been developed and integrated into a two‐man portable autonomous underwater vehicle (AUV) for geophysical and archeological surveys. The compact system collects data from a Geometrics microfabricated atomic magnetometer, a total‐field atomic magnetometer. Data from the sensor is both stored for post‐processing and made available to an onboard autonomy engine for real‐time sense and react behaviors. This system has been characterized both in controlled laboratory conditions and at sea to determine its performance limits. Methodologies for processing the magnetometer data to correct for interference and error introduced by the AUV platform were developed to improve sensing performance. When conducting seabed surveys, detection and characterization of targets of interest are performed in real‐time aboard the AUV. This system is used to drive both single‐ and multiple‐vehicle autonomous target reacquisition behaviors. The combination of on‐board target detection and autonomous reacquire capability is found to increase the effective survey coverage rate of the AUV‐based magnetic sensing system.

This article details recent maritime archaeological research off the town of Elmina in coastal Ghana. Founded in 1482, Elmina Castle was the first and largest European outpost in sub‐Saharan West Africa, and remained a centre of maritime trade for almost four centuries. Survey and diver investigations led to the discovery of several sites, including a shipwreck dating to the mid 17th century, which is characterized by a mass of trade goods, cannon and buried hull remains. A second Dutch vessel dating to c.1700 was documented after its discovery during dredging operations in the Benya Lagoon adjacent to Elmina. These sites present an opportunity to study ships and cargoes involved in the West African trade.

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