Autonomous robotic networks require communication links among robots and between the robots and a central unit. These links are used for command & control and for cooperative data retrieval. Such communication links must operate reliably in all conceivable environments in space and underwater, sometimes over long distances. Both in space and underwater, the environmental conditions are very different. The environmental conditions have a strong influence on the propagation of a communication signal, for instance in form of multipath propagation, fading and shadowing. Electromagnetic signals are suitable for communication in space and under atmospheric conditions. Under water, however, acoustic communication methods are typically used due to the considerably lower attenuation. Despite the different environmental conditions in space and under water, the requirements for a communication system are similar for robotic teams in these areas: A suitably high data rate must be provided with high reliability, availability and sufficiently low latency. Based on existing technologies - such as mobile radio, WiFi and acoustic underwater communication - we develop communication modules that reliably network a team of robots in different environments with suitable technologies.