Measurements of temporal variations in the total geomagnetic field were made at sea on the Abyssal Plain off Nova Scotia, Canada, during 1972 and 1973 from specially designed magnetometers housed in moored surface buoys. Comparison between the simultaneous recordings from sea and land stations shows enhancement in the land recordings from 10 min to 2 h periods with a maximum value around 30 min period. The trend of this enhancement is similar to that observed between Sable Island and Dartmouth and supports the previous interpretation of the presence of a high conductivity structure under the continental shelf. Comparison between the recordings made at sea and on land during the total solar eclipse of July 10, 1972 shows a phase lag of 11 min in the recordings at sea. This phase lag seems to agree with the eastward migration of the totality during this time.