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 order to carry out oceanographic observations, the performance of the vehicle was re-improved. This paper presents details of re-modifications of the vehicle, and oceanographic observations carried out at the west sea-area of the Goto islands in Nagasaki Prefecture and in the East China Sea.