What is the significance of a vessel's red light at night?

A vessel's red light at night is significant because it indicates the vessel's port side. The use of colored lights is essential for maritime navigation and safety, allowing other boaters to determine the position and direction of the vessel. In this context, the port side is the left side of the vessel when facing forward, which is why the red light is used to signify it.

This color coding is part of the rules established by the International Regulations for Preventing Collisions at Sea (COLREGs), which ensure that vessels are easily identifiable to each other during nighttime operations. Understanding which side is indicated by the red light helps other boaters maintain safe distances and avoid collisions in shared waters.

Other options do not accurately convey the purpose of the red light. For example, the starboard side is indicated by a green light, and an anchor light is specific to vessels that are not under way, while movement is generally indicated by navigation lights completing a full configuration, including both colors.