Unmanned underwater vehicles (UUV), sometimes known as underwater drones or uncrewed underwater vehicles (UUVs) are submersible vehicles that can operate underwater without a human occupant, usually categorized as uncrewed maritime vehicles (UMSs). These vehicles may be divided into two categories: remotely operated underwater vehicles (ROUVs) and autonomous underwater vehicles (AUVs). ROUVs are remotely controlled by a human operator. AUVs are automated and operate independently of direct human input.