Final answer:
When you see a lighthouse while operating a vessel, you must use it as a reference point to navigate safely.
Step-by-step explanation:
In the given scenario, the marker being referred to is a lighthouse. In boating and navigation, a lighthouse is an important navigational aid that helps mariners determine their position and avoid potential hazards.
When you see a lighthouse while operating a vessel, you must use it as a reference point to navigate safely, especially during nighttime or low visibility conditions.