Gravity measurements at sea are considered to be made on the geoid. The free‐air anomalies are then determined by subtracting the theoretical gravity values predicted on a reference ellipsoid from the observed values. The gravity effect due to the height difference between the geoid and reference ellipsoid and the mass between them is known as the “indirect effect.”; The result of applying the indirect effect to surface ship‐derived gravity anomalies in the North Atlantic Ocean demonstrates the importance of its inclusion for regional studies involving mantle processes.