In recent years, coral cover has been decreased by the impact of bleaching due to high water temperature, red-soil runoff, water pollution, and coral-eating starfish outbreak. It is necessary to appropriately measure, observe, and sample seawater. To succeed in these tasks, underwater robots should have a function of responds flexibly in solving problems. Underwater tasks are summarized as follows: (1) acquiring images and environmental information using cameras and sensors, (2) collecting objects and other necessary work using robot hands. Manipulator should be attached quickly to underwater robots as needed. So we have been developing “an easy-removable underwater manipulator.” The manipulators is easy to maintain because all electric components – DC motors, motor controllers, etc. – are in a pressure-resistant vessel, the manipulator has only one cable, and the manipulator is easy to attach and detach. In this paper, we illustrate the manipulator design and performance test results.
