Interactions between different kinds of actors engaged in outer space and ocean exploration and exploitation can be grouped into five major categories of activities. These activities reflect the dominant interests of all the participants, and they are treated at a level of generality which facilitates comparison. The categories of activities are: i) management and regulation of common resources; 2) exploitation of specific resources; 3) coordination and financing of research, including exploration and experimentation at the international level, and arrangements governing the exchange of information gained; 4) preservation of national and international security; and 5) recreation and the control of pollution.