Abstract: The present invention relates to an illuminating device that will create a continuously moving ripple effect on the area illuminated. The device comprises a patterned endless belt transported on a pair of driven rollers. One side of the belt is illuminated preferably by a point light source. As the belt is driven, the patterns on the two sides pass each other in opposite directions. This creates a rippled light effect. The device is particularly well adapted for use with an aquarium to simulate underwater, the effect caused by ambient light shining through surface ripple and waves upon the bottom of a body of water.