Global Underwater Drone Market Size study, by Type (Remotely Operated Vehicle (ROV), Autonomous Underwater Vehicles (AUV), and Hybrid Vehicles), Application (Defense & Security, Scientific Research, Commercial Exploration, and Others), Propulsion System (Electric System, Mechanical System and Hybrid System), and Product Type (Micro, Small and Medium, Light Work-Class, and Heavy Work-Class) and Regional Forecasts 2020-2027