illumination systems that include a plurality of illumination devices disposed within a water environment . such illumination devices having a tube filled with water , at least one light source positioned to project light into the tube , and connected to the illumination devices via light carrying connectors , include one or more voids within each tube wall which extend substantially longitudinally and cause light incident below a critical angle to be reflected hack into the tube . projected or reflected light above a critical angle that strikes a portion of the wall without a void is transmitted through the tube wall . by adjusting the ratio of voids to non - voids light can be delivered in a controlled manner .