Fast and parameter-light rare behavior detection in maritime trajectories

•A scheme cross trajectories, vessel attributes and the movement context for detecting rare behaviors through preprocessing, kNN-based clustering, and verification.•Only extremely few anomalies are useful which are rare behaviors.•The interactive detection process requires an instant response that is a big challenge for.•The more similar trajectories gather in an Area of Interest, the less probability of anomalies they are.•The small reachability distance values have limited effect on lrd.