Running lights, within marine context, refer to the specific kind of lighting fixtures that are mandatorily installed and operated on various types of water vessels such as boats and ships. These lights must be illuminated from sundown to sunup while the vessel is underway. Their primary function is to enhance visibility and to communicate the vessel's size, orientation, and status to other vessels operating in the vicinity during darkness or conditions of reduced visibility. Predetermined rules and regulations dictate the location, color, and visibility range of running lights, helping avoid potential collisions and ensuring the safe navigation of waterways during nighttime or low-light conditions. They typically consist of a combination of red, green, and white lights that illuminate specific parts of the boat: green on the starboard (right) side, red on the port (left) side, and white at the stern and/or masthead.

1. Fred ensured that the running lights on his yacht were fully functional before setting sail at dusk, to make his boat visible to other vessels during his night journey. 2. On her maiden nocturnal fishing trip, Lucy was careful to leave the running lights on her boat, to indicate her presence to other boaters and to comply with maritime safety regulations. 3. During our overnight sailing trip, we noticed a boat in the distance by its prominent running lights, helping us steer clear and avoid a potential collision. 4. The Coast Guard routinely checks if water vessels are using their running lights between sundown and sunup as a way to promote safety and navigation in the dark. 5. Before embarking on our evening canoeing expedition, we installed temporary running lights on either end of the canoe, ensuring we were visible to larger watercraft in the moonlight.

Running Lights, which are mandatory for boats operating between sundown and sunup, are designed not only to improve visibility during nighttime, but also to communicate the type, size, and direction of the vessel to other boats in the area. This fascinating and crucial feature of maritime navigation dates back to British regulations of the 19th century. The configuration of these lights, such as a red light on the left (port) side and a green light on the right (starboard) side, were adopted universally to prevent collisions at sea, paving the way for safer global exploration and trade. Interestingly, these color choices were not random - red was chosen for the port side because it was traditionally considered a warning color, and green for starboard following the traffic light convention of 'green for go'.