In recent years it has become evident that ocean data in time and space is required to make predictions of environmental changes on earth. As one method of acquiring data, we propose a virtual mooring system using an underwater glider, and have developed a prototype vehicle called “BOOMERANG” which can glide back and forth between the sea surface and the seabed collecting ocean data. In this paper, the research on course control of a disk type underwater glider is shown for improvement in the performance of virtual mooring.