Many boaters on the water seem to be ignorant when it comes to what all the marks and buoys out there really mean. They are the ones that who endanger others as well as themselves.
If you are unfamiliar with channel markers, remember the "Three R's." The 3 R's: "Red Right Returning" mean when coming back to port you should keep the red marks to the starboard (right) side of the boat and the green marks to port (left) side of the boat.
Following this simple rule will keep you in the channel.
Obviously, when heading out to sea, the opposite would be true. One word of caution though, if you are entering a channel in certain foreign, non-US countries, the opposite rules may be in effect.
What if you cannot see the color of the marks? The red day marks are triangles and the red buoys are nun buoys, tapered from wide to narrow at the top,
while the green day marks are square and the green buoys are cans, square shaped. So, even if you cannot tell the color, you should be able to tell by the shape.
It can be slightly more confusing if you are traveling on the IntraCoastal Waterway and you are neither leaving or entering port. The basic rule here is to keep the "Green to Seaward." As an example, if you are traveling from Miami to Jacksonville (Northbound), you would keep the Green Marks to the starboard side (right) and the Red Marks to the port side (left), or "Green to Seaward."
If you were cruising from Naples on the West Coast Northbound to Clearwater, you would keep the Green Marks to the port side (seaward) and the Red Marks to Starboard (landside).
Be aware of your markings and you'll be a safer boater for everybody.