What does a yellow square marker indicate to a vessel?

A yellow square marker indicates to a vessel that it should keep the marker on the left side when passing. These markers serve as navigational aids that provide critical information about safe passage, helping boaters to navigate waterways safely.

In the context of boating, maintaining the proper side of a marker is essential for avoiding collisions and ensuring that vessels adhere to the established navigation protocol, which fosters a safer boating environment. These markers can often be found in areas with specific navigational rules, signaling safe passage for vessels in either direction.

The other options represent different types of markers or signals that indicate various navigational rules or hazards. For example, a marker indicating to "proceed with caution" or "danger ahead" would provide different guidance than what is indicated by a yellow square. Similarly, "refer to local regulations" pertains to areas where specific local rules may apply, typically conveyed through other types of markers or signage. Understanding marker colors and shapes is vital for safe navigation on the water.