We present an agent-based system for modeling, analyzing and reasoning in the maritime domain with the emphasis on detecting, anticipating and preventing illegitimate activities, such as contemporary maritime piracy. At the core of the system is a data-driven agent-based simulation which combines a rich array of sources of real-world piracy-related data with simulated operation of thousands of vessels of different types in order to create a rich model of maritime activity. The simulation is integrated with a range of advanced adversarial reasoning methods for analyzing illegitimate activities and for planning active counter-measures. In combination with experiment support tools and a powerful presentation frontend based on Google Earth, the system provides a complete testbed for the development and evaluation of counterpiracy methods based on the multi-agent approach.