Recreational scuba diving is a highly social activity where divers are encouraged to work in groups of two or more people. Though collaborative, divers are unable to freely and naturally communicate. Additionally, the distortion of sensory information (e.g. distances and sounds cannot be judged as accurately underwater) affects the ability to keep track of critical information which impairs their ability to engage in this underwater world. We have studied and designed a fault tolerant system, including the software, the device, and the network, to foster underwater communication. We studied the technology required, the software design for both single user and multiple users, as well as, the network design in order to support such a system. In the thesis, we have set up and analyzed the result of three user studies and a simulation to investigate the viability of the proposed design.