Soft robots apply compliant materials to perform motions and behaviors not typically achievable by rigid robots. An underwater, compliant, multi-segment continuum manipulator that can bend, swallow, disgorge is developed in this study. The manipulator is driven by McKibben water hydraulic artificial muscle (WHAM). The mechanical properties of the WHAM are tested and analyzed experimentally. The kinematics model, which concerns about the variable diameter structure of the soft grippers, are established to simulate the behaviors of the manipulator among the bending, swallowing and disgorging procedure. A mouth-tongue collaborative soft robot assembled with another single-segment soft robot arm is presented. And its functions are experimentally testified. The distinctive functions were verified according to the experimental results.