What distinguishes a cardinal mark's position?

A cardinal mark's position is primarily distinguished by the top shape of the mark. In the IALA Maritime Buoyage System, cardinal marks are used to indicate safe water on specific sides of navigational hazards, and their shapes provide important information regarding the direction of safe passage.

For example, a north cardinal mark has a conical top, while a south cardinal mark has a flat top. These shapes help mariners visually identify the marks during navigation and understand how they relate to nearby hazards or features. The distinct top shapes convey critical navigational information, guiding vessels around dangers by indicating the safe direction to navigate.

While the color of the buoy and the sound it emits also have their own significance in navigational systems, the shape of the cardinal mark is the key distinguishing feature that directly denotes its purpose and the information it provides about the surrounding waters. Similarly, the height above water may influence visibility but does not convey the specific navigational context that the shape does.