Dive lights serve several purposes. The obvious uses are illuminating dark crevices between rocks and night diving. But another use is to bring out the natural colors of objects underwater.

As you'll learn during the "Physics" chapter, water absorbs colors of the light spectrum as you descend, so the deeper you dive, the fewer colors you'll see. Carrying a light allows you to see colors you'd ordinarily never know existed underwater.

Dive lights use lubricated o-rings to maintain a watertight seal. Handle these o-rings with care when replacing batteries. Sand, salt crystals, and even strands of hair can create a leak that will result in a flooded light.