This paper develops a virtual platform of an underwater manipulator mounted on a submersible vehicle via the three-dimensional simulator “Webots” for teleoperation through a replica master arm. The graphical, kinematic, and dynamic models of the manipulator refer to a master-slave servo hydraulic manipulator with seven functions, consisting of six degrees of freedom and a parallel gripper, while the “Jiaolong” deep-manned submersible vehicle, operating below the sea surface down to 7000 m, is chosen as the underwater manipulator carrier. This study uses the virtual platform for training an operator to telepresence control the virtual manipulator to complete basic tasks in subsea environments. When training the operator, one has to consider uncertain external disturbances and the visual impacts that stem from subsea environments. In order to demonstrate the feasibility and effectiveness of the virtual platform, one designs two typical underwater operational tasks: grasping a marine organism sample and reaching at a given position. This paper presents the comparative studies: 1) the performances demonstrated by remotely controlling the virtual manipulator and the real manipulator; 2) the operating performances delivered by three operators before and after training when using the platform.