Multibody marine robots, representing a promising research and development area, have gained acute attention and response from civil and military fields. A multibody marine robot is a multibody system composed of multiple single-body marine robots (defined as a unit) in a certain topology. Such a system is generally characterized by underactuation, hyperredundancy, power distribution, modularization and so on. Compared with traditional single-body marine robots, multibody marine robots can carry greater loads and have more forms of motion, so they can meet more specialized functional requirements. At the same time, they also have more complex hydrodynamic characteristics due to their unique structures and motion forms. In this paper, the types, features, and hydrodynamic characteristics of typical multibody marine robots are reviewed and summarized based on the connection structures between units. In addition, the development trends of multibody marine robots are analyzed and discussed. This review work anticipates positive attention from future readers regarding multibody marine robots, which represent an important subarea of marine robots.