What does a green buoy mark in navigation?

In navigation, a green buoy indicates the port side of a waterway when entering from the open sea or moving upstream. This is part of the IALA (International Association of Lighthouse Authorities) buoyage system, which uses a color-coding convention to help mariners identify safe navigation routes. Green buoys are numbered with even numbers, and they serve to aid in marking the channel and provide guidance to boats and vessels, ensuring they navigate safely without straying into dangerous areas.

The buoy’s primary purpose is to guide vessels toward the correct side of the channel; thus the mariner sees that they should keep the green buoy on their port (left) side while navigating upstream. This is foundational knowledge in maritime navigation and is integral to ensuring both safety and compliance with navigation regulations. Understanding buoy colors and their meanings is crucial for successful navigation and avoiding hazards while at sea.