This paper presents the development of a full ocean depth master-slave hydraulic manipulator system for marine engineering and research in the harsh hadal environment. Three basic modules of the slave arm including a linear cylinder, a single-vane swing cylinder, and a new wrist joint are designed. The electronic system and software are developed then. Laboratory experiments on the single-vane swing cylinder and the new wrist joint were carried out to verify the performance of new joints. Additionally, a 11000 m pressure experiment is conducted, and the results demonstrate that the full ocean depth hydraulic manipulator system works well in the 11000 m environment
