An environmentally sealed closure, such as a terminal for terminated ends of fiber optic cables, includes a housing having a wall defining an interior volume. A floating sealing assembly is provided including a first plate, a seal member and a second plate arranged in a stack within the interior volume. The seal member has an outer sealing edge for contacting the wall of the housing, which may be straight and/or chamfered. Fiber optic cables extend through the sealing assembly so that the terminated ends are within the splice area. The floating sealing assembly is compressed so as to place the outer sealing edge of the seal member in sealing contact with the wall of the housing. When a pressure differential exists between the splice area and the outside of the housing only one of the first or second plates moves along the longitudinal axis to further compress the seal member and increase sealing between the outer sealing edge and the housing wall.