What type of lights do submarines use?

Submarines utilize a combination of running lights and flashing yellow lights to ensure visibility and safety while navigating underwater and on the surface. Running lights are crucial for indicating the direction a vessel is moving and are used to signal the presence of the submarine to nearby craft, helping to prevent collisions. The inclusion of flashing yellow lights serves as an additional warning signal, often used when a submarine is operating in or near areas where they could pose a hazard to other vessels or when they want to signify their presence more prominently.

The other options do not align with the established practices concerning submarine lighting. Submarines do not restrict themselves to only red lights, as that would limit their operational signaling capabilities. Flashing blue lights are not typically associated with submarines, and while green and white lights are relevant for certain types of vessels (like fishing boats), they do not represent the standard lighting for submarines. Thus, the combination of running lights with a flashing yellow signal is essential for their operations while maintaining safety at sea.