In an air cell of a buoyancy compensator an outer protective bag has a section of double layer construction. In the double layer area, two panels of elastic material are each juxtaposed adjacent a panel of non-elastomeric material. The elastic panels are spaced at a distance of each other such that during expansion when the elastic panels are at their limit, there is still an adjacent layer of non-elastomeric protective material. If a sharp object penetrates the elastic panel, it will not puncture the inner air cell unless it can also pierce the protective bag non-elastic layer.