A regulatory marker with a diamond shape and a cross through it indicates what?

A regulatory marker that is diamond-shaped with a cross through it signals that the area is off-limits to vessels. This type of marker is used to communicate restrictions or prohibitions, ensuring that boaters understand where they may not operate their vessels. The clear visual of the crossed-out diamond serves as a warning, prompting operators to stay clear of that specific area for safety reasons or to protect sensitive environmental regions. This is an essential aspect of navigating safely and responsibly on waterways.