What type of buoy does not emit light?

A nun buoy, which is typically a conical shape and colored red, does not emit light. These buoys are used primarily to mark navigational channels on the right side when approaching from the sea. They serve as aids to navigation, providing visual cues for mariners, but they are not equipped with lights.

In contrast, safe-water buoys and lighted buoys are specifically designed to provide important navigational information and often include lighting or specific markings to enhance their visibility. A can buoy, which is cylindrical and colored green, can also serve a similar function in marking channels but does not typically have a light feature. Thus, the nun buoy is distinct for its lack of lighting, making it a clear choice for this question.