What color buoy marks safe passage on the port (left) side?

A red buoy marks safe passage on the port (left) side of a vessel. In navigation, buoys are used to indicate safe routes and to mark hazards. The conventional system in North America follows the "IALA A" buoyage system for inland and coastal waters, where red color signifies the right side when returning from sea, and thus it is always kept on the starboard (right) side of the vessel. However, in terms of marking the port side, a vessel should pass red buoys on its left side when navigating in the correct direction towards a safe harbor. This convention helps ensure safety and consistency in maritime navigation, allowing boaters to maintain proper course and avoid hazards.

The other colors such as green, yellow, and blue have different meanings in navigation and do not indicate safe passage on the port side. Green typically indicates starboard (right) markers, yellow is used for special purpose buoys, and blue might indicate navigational markers for various purposes but does not define a buoy's position in the context of safe passage like the red buoy does. Knowing this can greatly assist in safely navigating waterways and understanding buoyage systems.