What is a buoy used to mark natural dangers or obstructions shoals or wrecks?

A buoy used to mark natural dangers or obstructions, such as shoals or wrecks, is typically referred to as a "hazard buoy." These buoys are designed to alert navigators to potential dangers in the water, ensuring safe passage for vessels. They are often brightly colored and may have specific markings or lights to enhance visibility, especially at night or in poor weather conditions. The presence of such buoys is crucial for maritime safety, helping to prevent accidents and groundings.