Which channel marker indicates the left side when entering a harbor?

The correct option for indicating the left side when entering a harbor is the Port Marker. In nautical navigation, the color scheme and shape of channel markers are standardized to help boaters safely navigate waterways.

Port markers are typically green, and they are intended to be kept on the vessel's port (or left) side when approaching the harbor. This convention is crucial for ensuring safe navigation, as it helps to delineate the safe routes through channels and harbors. Recognizing port markers is essential for any navigator to avoid groundings or collisions, especially in unfamiliar waters.

While the other options describe various types of channel markers, they do not specifically designate the left side for navigation purposes as effectively as the Port Marker does. Safe Water Markers, for example, indicate the presence of safe water but do not give direction. Right Channel Markers indicate the opposite side (the starboard side), and a Left Channel Marker does not exist in standard terminology. Thus, understanding that the Port Marker indicates the left side reinforces the importance of using the correct terminology and knowledge in navigation.