This paper describes the development of the underwater robot platform for exploration work in the strong current. In order to minimize the drag force as 3.5knots, the platform is designed to have discus-shape outline and the projected area of the platform is minimized. Furthermore, the thruster are deployed symmetrically, which is advantageous for hovering and attitude control in irregular current change. By considering hydrodynamics and structural mechanics, moreover, it is shown that the platform gains sufficient thruster force and structural safety. Manufacture of the platform is accomplished and the performance test in water tank is under preparation.