Abstract: An underwater light fixture and a method for making the underwater light fixture are provided. The method includes assembling a light fixture in a housing, leaving a fastener out of the light fixture, wherein an opening for the fastener fluidically couples to open volume in the housing. The housing is placed in a vacuum chamber, and a vacuum is pulled on the vacuum chamber to remove air from the open volume of the housing. A dry gas is introduced into the vacuum chamber to fill the open volume in the housing, and the fastener is installed in the light fixture to seal the open volume.