A system and method for cooling electronic devices disposed with the innermost volume of a fluid-tight sealed enclosure. Thermally conductive fluids that fill one or more volumes of said sealed enclosure may be circulated away from said sealed enclosure to an external heat exchange mechanism. The innermost volume of the sealed container contains one or more single phase or multi-phase thermally conductive fluids, which may be circulated passively by convection or actively by means of a pump, bubbler, fan, propeller or other means. Pressure balancing mechanisms may be included to maintain suitable pressure of gaseous fluid in a volume of the sealed container.