What should you ideally have when your primary diving light fails?

Having a backup light is crucial for safety during night diving or in limited visibility conditions. When the primary diving light fails, a backup light provides an immediate source of illumination, helping divers navigate and avoid potential hazards in low-light environments. This redundancy is a key safety measure in diving, as visibility can dramatically decrease underwater, leading to disorientation or an increased risk of accidents.

While having a diving buddy is also important for safety, and they can assist during such situations, the primary purpose of a backup light is to directly address the issue of poor visibility caused by the failure of the main lighting equipment. Similarly, a surface marker buoy is useful for indicating the diver's position on the surface but does not aid in navigating or illuminating underwater environments. A dive computer provides valuable information on depth, time, and no-decompression limits but does not solve the issue of visibility itself. Thus, a backup light is the best immediate resource to have in the event of a primary light failure.