Characteristics of the ocean are considered in terms of U.S. social, scientific and ecomomic priorities and in terms of the measurements that can best be made from a spacecraft. The kinds of information needed to advance the basic ocean sciences, to improve marine transportation and fisheries operations, and to provide information for pollution control are discussed. These information needs were related to sensor concepts and an optimum sensor complement is presented, together with orbital considerations. The data-gathering capabilities of an oceanographic spacecraft were considered in relation to those of terrestrial oceanographic programs, using airborne, surface, and submarine platforms. Data management problems are discussed and are considered to be solvable with current technology.