Cardinal marks are used to show on which side of the mark it is safe to pass. They may also show where to find 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. They come in a variety of shapes and sizes, e.g. a beacon or buoy.
A mark erected on, or moored on or above an isolated danger (such as a rock or reef) which has navigable water all round it.
These are used to indicate an area of special significance, such as a spoil ground, cable or pipeline, military exercise area or an ODAS (data collection) mark.
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 Hazard to Navigation. At night it is lit by an alternating yellow and blue light. If you see this mark please keep clear and navigate with caution.