Abstract: An underwater swimming pool illumination system includes a lighting assembly having a lamp unit installed within its rear portion in a waterproof enclosure; and the lamp is connected to a low voltage battery. The waterproof enclosure may be at the bottom of a strut in an inverted L-shaped assembly, where the upper portion is a base which is fitted to a pad by a bayonet-type connection. The battery may be installed in the base, in which case the lighting assembly may be removed away from the pool to have the battery charged; or the battery may be remotely installed with a wire connection to the pad and lighting assembly. In either case, the installation is such that the lamp is completely electrically isolated from any alternating or ripple currents; either by physically removing the lamp from the pool for battery charging, or by a DPDT switch which either connects the battery to the lamp or to the charging circuit. This, in either case the battery is charged in a place remote from the swimming pool.