Software development for intelligent underwater robots is one of the most emerging technologies to support human activities underwater. A versatile test bed named “The Twin-Burger” was constructed in 1992 at the Institute of Industrial Science, the University of Tokyo for software development and verification in realistic environment. The Twin-Burger is a fully autonomous underwater robot which measures 1.54 m long and weighs approximately 120 kg in air. This paper describes the design philosophy of the robot and its hardware and software systems in detail. The Distributed Vehicle Management Architecture (DVMA) is proposed as a software architecture for the Twin-Burger to provide a mechanism to generate a sequence of behaviors for a commanded mission while handling the hardware interfaces in real time. Mission execution experiments were carried out to verify the architecture's effectiveness. It is shown that the Twin-Burger behaves appropriately according to the mission and environmental conditions by the DVMA.