Cardinal marks are used to show on which side of the mark it is safe to pass. They may also display the deepest water in an area, a bend or junction in a channel, or mark the end of a shoal. Cardinal marks should be passed on the indicated side of the mark.
When entering a harbour, keep the red marks on your left (port) and green on your right (starboard). When leaving, the opposite applies.
These marks show safe navigable channels and come in a variety of shapes and sizes.
Isolated danger marks
An isolated danger mark is erected on, or moored on or above, an isolated danger (such as a rock or reef).
Check your chart for the extent of the danger.
Emergency wreck marking buoy
If you see this buoy in Northland waters, it has been deployed to mark a submerged wreck and therefore indicates a serious navigational hazard. At night it is lit by an alternating yellow and blue light. You must keep clear and navigate with caution.
These are used to indicate an area of special significance, such as a spoil ground, cable or pipeline, military exercise area or a data collection mark.