The majority of magnetometer surveys are undertaken with a gradiometer which measures the magnetic gradient between two sensors (magnetometers) arranged on a horizontal separation, normally 1m or 2m apart.

Readings can be automatically logged allowing large amounts of data to be recorded and stored quite rapidly.

Surveys are usually undertaken along predetermined gridlines, logging at an average of four readings per metre.

Post-processing of data on-site allows the survey results to be monitored and modified as required.

Magnetometers are also used in a broader prospecting role to initially locate areas of 'magnetic activity' and also to help determine the extent of anomalies associated with previously identified features.

Magnetometry is also used for the detection and mapping of all sizes of ferrous objects.

This includes anchors, chains, cables, pipelines, ballast stone and other scattered shipwreck debris, munitions of all sizes (UXO), aircraft, engines and any other object with magnetic expression.

Objects as small as a screwdriver can be detected provided that the sensor is close to the seafloor and within practical detection range.

Interpretation of results can be problematic, especially when determining if the anomaly is geological or archaeological and the technique is dependent on local soil type and geology for success.