NOVELTY - The method involves storing lighter than air (LTA) balloon (115) and payload for the LTA balloon in an underwater storage and launch container (111), and providing a source for a supply of LTA gas. The source is operatively connected to the balloon. The launch container is positioned in an underwater location. The balloon is deployed by being filled with the gas, and the balloon is released from the launch container to ascend through water to a water surface (112) and to an untethered altitude of 10,000 meters above the surface to be difficult to detect the balloon.    USE - Method for deploying an LTA balloon to provide hydrogen utilized as motive gas and prime mover fuel in an aerial/air vehicle in a subsea environment.    ADVANTAGE - The method enables the hydrogen in compressed state to be lighter than seawater and to be buoyant to allow the balloon to be remained upright and pull away from the storage and the launch container, thus eliminating requirement for supporting the balloon's envelope during launch by a launch crew for surface-launched and shipboard-launched balloons. The method enables positioning the launch container such that the balloon can escape upward by arranging the launch container to make the balloon to be bottom heavy, so that the launch container is positioned inopportunely on a seafloor by initiation of hydrogen generation to lighten the launch container at an end and the launch container can be opened to accommodate escape of the balloon during opening, thus allowing multiple balloon launches to be performed from a single storage and launch container to maintain balloon coverage over a particular area. The method enables utilizing the gas to provide lift, so that system volume can be minimized and storage life is maximized by using borohydride or metal hydride to provide generation and delivery of the hydrogen and to allow the hydrogen to be stored without leakage indefinitely by releasing the gas when desired through chemical reaction in presence of catalyst, thus increasing storage life of the gas before pre-launch deployment for storage of the vehicle before underwater deployment and after pre-launch deployment of the balloon at a launch site. The method enables rising the balloon above the surface and supporting a diver with the diver's head above the surface to provide location information by providing an above-water location for emergency locator transmitter transmissions and by using the balloon to make the diver easy to spot.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) an underwater balloon launch assembly comprising a hydrogen generator    (2) a method for deploying a high-altitude communication relay.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of an underwater storage and launch container being pulled upward during fill process.    Underwater storage and Launch container (111)    Water surface (112)    LTA Balloon (115)    Fill tube (119)