What is the identification for a buoy that has two black balls on top?

The identification of a buoy that has two black balls on top is indeed associated with an isolated danger buoy. An isolated danger buoy is used to mark a specific hazard to navigation, such as a rock or a wreck, that is surrounded by safe water. The two black balls on top of the buoy help to indicate this, providing a clear visual cue to mariners that they should navigate with caution in the area.

The purpose of this buoy is to alert boaters that while the area around it may be safe, the specific location marked by the buoy poses some form of danger. It is essential for safety and navigation, ensuring that operators are aware of potential hazards that require their attention. Understanding the indicators of different buoys is crucial for maintaining a safe passage on the water.