This research monograph describes a large programming project in which an underwater organism, capable of perceiving, learning, deciding, and navigating, is computationally simulated. The developed computational model serves as a contemporary theory of perceptual-motor performance, embodying much of what is known about human vision and some of what is known about other cognitive processes. This artificial intelligence project has substantial contributions to make to the development of autonomous underwater vehicles. It also makes a specific theoretical statement about the organization and nature of organic perceptual motor systems that may be useful to psychologists, neuroscientists, and theoreticians in a number of other fields.