What type of buoy is used to mark controlled areas?

The circular buoy is specifically designated for marking controlled areas in navigable waters. These buoys serve important purposes such as indicating zones where specific rules or regulations apply, which might include areas for swimming, no-wake zones, or other restrictions pertinent to boaters. The shape and color of the buoy convey this information clearly to those on the water, ensuring that they can quickly recognize and understand the nature of the controlled area.

In contrast, other buoy shapes serve different functions. The square buoy typically indicates information related to navigational hazards or may denote certain points of interest, while the diamond buoy usually signals caution and may indicate the presence of an obstacle or danger. The crossed diamond buoy often represents areas where boating is prohibited altogether, rather than simply indicating controlled areas. Thus, the circular buoy is the correct choice for signifying zones with specific control measures in place, helping to maintain safety and regulation compliance on the water.