The development of a compact, battery-powered sensor platform intended for underwater applications and using hydroacoustic communication is reported. The design and manufacturing of the device is described with emphasis on the method used to monitor and reduce the current consumption. The devices have been encapsulated in epoxy and evaluated under field conditions, which showed that the system is usable in its current form. In addition to hardware improvements, e.g., in order to increase battery lifetime, the next generation of the system will implement forward error correction and improved receiver signal processing to reduce the impact of signal reflections.