Underwater communication is necessarily useful for various application domains such as saving of human lives from underwater disasters, marine resource exploration, underwater military fields, underwater environment or ecosystem monitoring, fish farm monitoring and management, etc. Even though the acoustic wave has been the main underwater communication media until now, several media such as optical waves, VLF/ELF waves, magnetic fields, and infrared rays also began to be treated as possible media for underwater communication. If these underwater communicate-possible media are used mixing together, the underwater communication can be much more reliable and efficient through complementing the disadvantages of each communication media with advantages of other communication media. In fact, mixing and using multi-media for underwater communication requires the data flow control in the connection process of different media due to their communication speed gaps and bandwidth differences, and, specially, in the flow control, the appropriate message fragmentation technique is required inevitably. For this reason, this paper presents a fragmentation framework and technique necessary to the flow control in the underwater multi-media communication. In addition, through its implementation and experiments, this paper shows the feasibility on the realization of the multi-media based underwater communication.