What action should you take if you see a buoy with a red square?

A buoy with a red square indicates that you are approaching a designated area where you should prepare to enter a federally marked waterway. This type of buoy serves as a navigational aid, conveying important information to boaters regarding the boundaries or entrances to specific channels where federal regulations may apply.

In this context, recognizing that the red square signifies entry into a federal waterway prepares a boater to adhere to the necessary rules and guidelines of that waterway, thereby ensuring safe navigation. Understanding this helps reinforce the importance of observing navigational aids and their meanings for safe boating practices.