A dive light is a light source carried by an underwater diver to illuminate the underwater environment. Scuba divers generally carry self-contained lights, but surface supplied divers may carry lights powered by cable supply . A dive light is routinely used during night dives and cave dives, when there is little or no natural light, but also has a useful function during the day, as water absorbs the longer (red) wavelengths first then the yellow and green with increasing depth. By using artificial light, it is possible to view an object in full color at greater depths.