Fluctuations in the Earth's magnetic field caused by ocean swell have been measured above the ocean's surface with total field magnetometers. The magnetic field measurements were made both from an oceanographic research tower and from a dual magnetometer system on an aircraft. The results are consistent with the theory of magnetic fields associated with ocean waves and swell as developed by Weaver (1965). Aeromagnetic measurements give a good estimate of the period of the dominant ocean swell and its direction of propagation. ¿ American Geophysical Union 1989