The past decade has shown a dramatic increase in the use of unmanned tethered vehicles in worldwide marine fields. These are used for inspection, debris removal and object retrieval.During the past ten years, the RCV-225 vehicle has become an industry standard as a small size, highly maneuverable, inspection tool. It is able to operate in very confined areas that would otherwise be inaccessible. In the past three years major subsystem changes have been made to the RCV-225 vehicle to further increase its utility. These improvements have included the high thrust motor, an FM telemetry system, a color television interface, an image size measurement system, improved on-line video annotation capability, and an emergency locator beacon which is automatically deployed upon tether cable severance.For more extensive underwater work the larger RCV-150 vehicle provides greater power, and operational versatility. As types of applications continue to increase for the RCV's, designs of the future vehicles will use the present baseline systems with their worldwide experience as starting points.