When you see a buoy with a number 5 with a flashing green light what should you do?

A buoy with the number 5 and a flashing green light indicates a navigational marker for vessels, typically signifying a safe passage or channel on the starboard (right) side when entering a harbor or waterway. If you are navigating, you should keep this buoy on your right side as you proceed. Always maintain a safe distance from the buoy and follow local navigation rules.