A tether control system for an inspection vehicle operable in a housing having a liquid medium is disclosed in the present application. The tether system includes a tether connected between the inspection vehicle and an electronic controller. A controllable buoyancy system associated with the tether is operable for moving the tether in a desired location. The controllable buoyancy system includes one or more floating bodies having a propulsion system and one or more buoyant elements having variable buoyancy capabilities.