What does a solid red light indicate in navigation?

A solid red light is used in navigation to signify the port side of a vessel when it is being approached from ahead. In maritime navigation, vessels often display different colored lights to indicate their position and direction. The convention is that a red light indicates the left side (port side) of a vessel, especially in the context of nighttime navigation. This helps other vessels determine how to safely pass, as they can identify the orientation of another vessel based on the colors of its navigation lights.

Understanding these signals is critical for avoiding collisions and ensuring safe navigation, especially in conditions of limited visibility. The other options describe different navigational aspects but do not accurately represent the meaning of a solid red light. For instance, a green light indicates starboard, various hazard indicators are not solely represented by solid red lights, and safe water is typically marked by a white light or a specific buoy color, rather than red.