A boat courtesy light is used to illuminate areas such as passageways, walkways, deck floor, companionway stairs, and low hanging ceilings. Courtesy lighting is intended to make navigating any area of a boat or vessel at night easier and thus reduce or prevent accidents such as slips, trips, and falls. Courtesy lighting is sometimes used to accent the interior and exterior of a boat or vessel and make it more visually appealing.

Courtesy lights should generally have a minimal footprint so they will not obstruct the room/walkway by protruding off the ceiling/wall. The use of directional, compact LEDs allows courtesy lights to deliver precisely controllable beams exactly where they are needed in a slim form factor without taking up much room. LED courtesy lights commonly come in the form of disc, panel, or strip. These luminaires utilize the onboard 12/24V DC power supply, implementing a DC-DC converter to regulate the LED load. The associated physical volume for such LED drivers is relatively small when compared with AC-DC LED drivers, and therefore the footprint of LED courtesy lights can be minimized as much as possible.

Courtesy lights often have stainless steel or thermoplastic housings designed to resist corrosion in even the most extreme saltwater environments. Luminous flux from the LEDs is regulated typically by an impact- and UV-resistant acrylic or polycarbonate lens. Boat courtesy lights are completely sealed to a typical IP67 rating. The luminaires are protected against the effects of temporary immersion in water.