Abstract : Long-endurance oceanographic sampling platforms such as gliders and profiling floats provide a new opportunity for acquiring acoustic signals from marine animals with immediate applications in conservation and mitigation. Our objective is to produce a reliable system for persistent passive acoustic monitoring of marine animals. The system, comprising both low-power hardware and acoustic processing software, will be extensible and can be incorporated in a variety of autonomous platforms. The design will be open and available for other researchers to adapt and extend.