This article describes the development of a hybrid autonomous vehicle capable of flying and navigating on ground terrain and water surface. This is achieved by combination of a typical coaxial tricopter with a flotation device, coupled with omniwheels and water propellers. The mechatronic design is presented, starting with the hardware component description, the supervisory control architecture and the redesign based on the hardware-in-the-loop simulation. The water-resistant autonomous vehicle uses one autopilot copter-component and another one for the vehicle/vessel. The supervising computer switches between these autopilots depending on the needed mode of operation using alterations in the firmware in designing the control effort. Simulation and experimental studies are offered to highlight the efficiency of the developed system.