Our knowledge of the oceans a hundred years ago was confined to the two dimensional shape of the sea surface. And the hazards of navigation presented by the irregularities in depth of the shallow water close to the land. The open sea was deep and mysterious, and anyone who gave more than a passing thought to the bottom confines of the oceans probably assumed that the sea bed was flat. Sir James dark Ross had obtained a sounding of over two thousand four hundred fathoms in eighteen thirty nine. But it was not until eighteen sixty nine when porcupine was put at the disposal of the royal society for several cruises, that a series of deep soundings was obtained in the Atlantic. And the first samples were collected by dredging the bottom shortly after this, the famous h m s challenger expedition established the study of the sea floor as a subject worthy of the most qualified physicists. And geologists at burst of activity associated with the laying of submarine cables soon confirmed the challenges. Observation that many parts of the ocean were two to three "miles deep, and the existence of underwater features of considerable.