The aim of the Duke of Edinburgh's lecture is to extend the horizons J. of navigational interest. I shall try to show how modern scientific methods are greatly increasing our understanding of how the oceans themselves work, and, at the same time, do all I can to maintain that this new knowledge is not just a matter of curiosity. If vigorously developed it will be of much practical use to seamen, and of great benefit to us all. The time is opportune. Scientifically inclined nations recently have been making organized all-round exploration of the human environment. As well as major Antarctic operations, and the rush to Space, there is growing realization that the oceans are coming within our grasp for major technical exploitation.