An unmanned autonomous submarine which can float, dive and move in water to perform various tasks. The submarine includes a pressurized cabin which is necessary for the diving and flotation system to work properly. This also helps to increase its sealing power against water leakage into the cabin. The submarine is autonomous, that is automatic and self controlled. It is propelled by water jet propulsion. It can be programmed to dive to preset depths, move along preset trajectories, and return to the base after completing the assigned tasks. A remote control option is provided in order to perform special tasks. The submarine is equipped with several sensors that can measure depth, orientation, attitude, location and speed. It is also equipped with an underwater video camera that can send wireless video pictures from underwater to a monitor above water surface.