The majority of marine gravity and/or magnetic data are 
collected in conjunction with other survey methods. Most marine gravity and magnetic survey work takes place as an addition to seismic surveys, but marine gravity and/or magnetic data are also collected on EM surveys, ROV projects, multi-beam bathymetric surveys, and other hydrographic projects. Advantages of having the gravity and/or magnetic data acquired in conjunction with other projects include the following:
1. Economy: The cost for adding the marine gravity and/or magnetic services to an existing survey is relatively low. In the stand-alone mode, the additional cost for a dedicated vessel with a positioning and bathymetry system can be substantial.
2. Regulatory Issues: Generally, adding marine gravity and/or magnetic services to an existing survey does not involve any significant additional permitting or licensing issues with the governing legal authorities.
3. Co-located Survey Lines: Having the gravity and/or magnetic data acquired along the same survey tracks as the seismic or other survey methods can be beneficial in certain multi-discipline enhanced processing and interpretation methods