In proposing the so‐called seismic or sonic method as a tool for the geologic investigation of ocean‐bottoms and margins, I am aware that I am recommending a method not widely known, and one practically untried for the purpose under consideration.The problem of working from the ocean‐surface, instead of from a land‐surface, will require the development of a special technique, but it presents no major difficulty; in fact, it has decided advantages. I am confident that the method can be developed into a tool equal or superior to any now at the command of the geophysicist, geologist, or oceanographer for investigating the constitution and structure of that great and almost unknown portion of the Earth—the ocea