If visibility were simply a matter of illumination, a diver’s headlight and flashlight would suffice. But a shipwreck is filled with silt and debris. The diver’s slightest movement—a reach for a dish, a kick with the fin, a turn to memorize a landmark—can stir the silt and disturb visibility. At times of such stark darkness, the deep-wreck diver is more a shadow diver, aiming at the shapes of a shipwreck as much as at the shipwrecks themselves.
