Provides a comprehensive review of techniques used to explore the oceans and examines what geophysical observations reveal about the structure and tectonics of the seabed and the Earth's interior. Exploration of the oceans using geophysical methods has had a profound effect on the way we view the structure of the earth and its behaviour through geological time. Geophysics has also played a vital role in the search for petroleum and other natural resources lying beneath the seabed. This volume looks at: the means of locating observations accurately and determining in detail the morphology of the sea floor; the powerful seismic techniques for imaging the Earth's interior from shallow coastal areas to deep-sea trenches; the gravity and magnetic fields over the oceans, heat flow, electrical and radiometric methods and measurements in offshore boreholes; geophysical observations on the development of the modern oceans, the structure of their deep basins, and the nature of their aseismic and seismically active margins. This book will be of interest to marine scientists and advanced undergraduates and postgraduates following courses on, or undertaking research in, geophysics, marine geology, oceanography, physical sciences, remote sensing, marine surveying and offshore engineering.