A yellow rectangle on a buoy indicates it is part of the?

A yellow rectangle on a buoy specifically indicates that the buoy is marking the Intracoastal Waterway (ICW). The ICW is a navigable waterway that runs along the southeastern and eastern coasts of the United States, providing safe passage for vessels by guiding them along specific routes. The yellow rectangle serves as a visual cue to boaters that they are in the area of the ICW, thus helping to maintain safe navigation.

While navigation systems use various buoy colors and configurations to convey different messages, the yellow rectangle is uniquely associated with the ICW, distinguishing it from navigational aids that may indicate other types of routes or hazards. This distinctive marking plays a crucial role in ensuring that mariners remain aware of their surroundings and can follow designated navigation paths safely.