original_query: What is a dive light and what is its purpose?
query: What is a dive light and what is its purpose?
answer: A dive light is a light source carried by an underwater diver to illuminate the underwater environment.  Its purpose is to improve underwater vision at depth, as water absorbs light, especially longer wavelengths like red.  Dive lights are routinely used during night dives and cave dives, but also during the day to see objects in full color at greater depths.