What is the function of cardinal mark buoys in navigation?

The primary function of cardinal mark buoys in navigation is to indicate safe water areas relative to hazards, such as rocks or shallow waters, and to help mariners determine the direction of safe routes. These buoys utilize a system based on cardinal directions—north, east, south, and west—to guide vessels safely past navigational hazards and towards deeper waters.

Cardinal marks are typically distinguishable by their color schemes and light characteristics, which provide clear signals regarding the safest course to navigate around obstacles. For instance, a north cardinal buoy, marked with specific colors and patterns, signifies that the safe water lies to the north of the buoy, while hazardous conditions are to the south.

The other options involve functions that are outside the scope of what cardinal mark buoys are designed for, such as providing anchorage locations, which is typically the role of different types of markers, guiding vessels with a broader navigational context, and signaling weather warnings, which may be addressed by other buoy systems or signals.