This maker indicates a mid-channel or safe water mark. This will usually be the first marker you see returning from sea. It will not have a number and may be lettered. It may be lighted or unlighted and may have an associated sound. The light (if lighted) will be white and will flash the Mo (A) sequence. (Morse Code Alpha). You may pass to either side of the marker.

This represents the next set of markers you might see when returning from sea. You should pass between them leaving the red marker on your starboard side. Remember "RED RIGHT RETURNING". The red "Nun" starboard side markers are even-numbered and, if lighted, have red lights. The green "Can" port side markers are odd numbered and, if lighted, have green lights.

This is a preferred channel or junction marker and indicates a bi-furcation in the channel. To navigate the preferred or primary channel, you should treat the marker as if it had all the characteristics of the color of the top band. If the top band is red, such as the one shown above, you would treat it as a red, starboard side marker (leave it on your right) to access the primary channel. If the top band is green, you would treat it as a port side marker to access the primary channel. If lighted, the marker would have a light the same color as the top band.

This is where it gets a little tricky. The yellow triangle and yellow square are dual purpose marks where the Intracoastal Waterway (ICW) and other waterways coincide. Now what?

Question 1: Between which markers and in which direction (right or left) would you turn to follow the ICW going north?
To enter the ICW in a northerly direction you would turn starboard (right) between red marker #4 with the yellow square and red marker #6.

Question 2: Between which markers and in which direction (right or left) would you turn to follow the ICW going South?
To enter the ICW in a southerly direction you would turn port (left) between green marker # 3 and green marker #5 with the yellow triangle.

Question 3: How do you know which direction to turn to go north or south?
The ICW is a special waterway which runs from New Jersey to Texas. Traveling from New Jersey to Texas is considered returning so you would have Red Right Returning when going "generally" south, or from NJ to TX regardless of compass setting. Now, remember those dual purpose yellow markers? (The yellow triangle represents a red nun buoy and the yellow square represents a green can buoy.) These are found, on the ICW, in areas where other waterways connect with or cross the ICW. When operating in the ICW, take note of the yellow triangles and yellow squares and treat them as the buoys they represent no matter what the color of the buoy they are on.

Representation for illustrative purposes only

Another way to remember this is to think of the ICW (the blue line) as a ditch just inland of the waters surrounding the US from New Jersey to Texas. You would always keep the yellow triangles or red markers on the land side and the yellow squares or green markers on the "green" ocean/Gulf side.

Also see the Basic Boating Safety Course
and The Coastal Navigation Course