This paper will include a discussion of seismic effects and measurements in ocean basins as determined from natural earthquakes and from explosions. Earthquake seismology has been related to problems of the oceans since its beginning. In fact, establishment of the international network of seismograph stations, suggested by John Milne in 1897, was due in large part to the correlation of submarine cable breaks with oceanic earthquakes. Much of the great destruction of life and property caused by earthquakes at the borders of oceans results from the great sea waves or tsunamis occasionally generated by them. Recently it has become possible to draw quantitative information about the structure of the sea floor and its underlying rock layers from study of the dispersion of earthquake surface waves along oceanic paths.