What shape is a marking buoy indicating danger?

A buoy indicating danger is marked with a diamond shape. This shape is universally recognized in boating as a warning signal to alert operators to hazards in the water, such as rocks, shallow areas, or the presence of another hazard that could be dangerous to vessels. The use of a diamond shape is standard in navigational signage, allowing for quick visual identification by boaters, which is crucial for safety on the water.

Other shapes such as circles, squares, and triangles do not communicate hazards in the same way. For example, circular buoys usually indicate information or direction, square buoys can signify general information, and triangular shapes are typically used to indicate specific types of navigational hazards or restricted areas, rather than dangers. Therefore, the diamond shape is the correct and standardized symbol for marking danger in aquatic environments.