An invention disclosed herein pertains to a thruster suitable for underwater vehicles. Such a thruster includes a steerable duct and propeller. The thruster motor, the two directional servo motors and all necessary electronics are contained in a single fluid filled and pressure compensated container. This is made possible, by a compact steering mechanism that allows the propeller and duct to be steered about the pitch and yaw axis of the vehicle and a spherical rolling seal which allows the fluid in the thruster to be maintained at a pressure of 2-5 psig. A gimbal that features a ring drive element enables efficient use of space. An actuation to drive the thruster may fit inside the ring drive element.