Abstract: An hybrid unmanned underwater vehicle comprises a body housing a controller; a vector thruster for propelling the body; deployable wings allowing the unmanned underwater vehicle to traverse by gliding as the unmanned underwater vehicle ascends and descends; a center-of-mass shifter for shifting a center-of-mass of the vehicle to allow the unmanned underwater vehicle to pitch up and pitch down; and one of a multi-stage buoyancy control system within the body and configured to adjust an apparent displacement of the unmanned underwater vehicle and an expandable outer shell configured to adjust an apparent displacement and therefore a buoyancy of the unmanned underwater vehicle.