A yellow buoy may mark which of the following?

A yellow buoy is commonly used to indicate a spoil area. Spoil areas are locations designated for the dumping or placement of dredged materials from waterways, which typically need to be avoided by recreational and commercial vessels for safety reasons. This color-coding is part of the navigational aids that help boaters identify specific regions and ensure they safely navigate around potentially hazardous or restricted zones.

In contrast, buoys that mark safe passages, restricted areas, or dangerous shallows may use other colors or markings that convey different meanings. Understanding the specific purpose of yellow buoys helps boaters recognize and respond appropriately to the navigation and safety messages they provide. It's important for boaters to be aware of these markings to avoid accidents and ensure safe navigation on the water.