Which mark indicates a cautionary area on nautical charts?

• A. Yellow, indicates cautionary area
• B. Magenta flash symbol
• C. Black and red, two black spheres
• D. Red and white vertical stripes

Answer: (A)

On nautical charts, color and symbols quickly signal what you should expect. A cautionary area is shown with yellow shading on the chart, which tells you there are hazards or conditions in that zone that warrant extra caution. It’s a general warning indicator, not tied to a specific buoy or light.

The other marks point to different features: the magenta flash symbol marks a special mark with a particular instruction or area of interest, not a broad caution zone; the two black spheres (and related black-and-red patterns) indicate isolated danger marks; and red-and-white vertical stripes designate a safe-water mark, which signals you can expect safe water around the buoy or point, not a caution zone. So the yellow shading is the best cue for a cautionary area.