What Does A White And Black Striped Buoy Mean In A Lake?

You're cruising across a lake on a sunny afternoon, the water stretching in gentle ripples around your boat, when a black-and-white buoy appears ahead. You might ask yourself: Is it marking a hazard, directing boat traffic, or something else? Buoys and other markers are part of an international maritime system called Aids to Navigation (AtoN). This system works similarly to road signs to help boaters navigate the waters safely. Instead of depicting symbols or words, these markers typically use colors and patterns to tell boaters when to slow down, where to turn, and which hazards lie ahead. If you see a buoy with vertical black and white stripes, that means there's an obstruction between the buoy and the nearest shore, per the BoatU.S. Foundation, and boaters should avoid passing between the marker and shoreline.

A buoy with alternating vertical black and white stripes is known as an inland waters obstruction mark. On inland waterways, such a mark designates where rocks, underwater debris, shallow water, or other obstacles make a seemingly open stretch unsafe to cross. This applies to lakes and rivers alike, so you might spot the buoy on a voyage down the Mississippi River, or while enjoying a day on one of the best American reservoirs for a scenic vacation. Going beyond the buoy can be dangerous as it can cause your boat to become stuck or damaged, and a sudden collision with a hidden obstruction could lead to injuries. 

If you're a seasoned boater, you might know that an older mark for the same type of hazard had red and white stripes. The older red and white obstruction marks were phased out by 2003, per the Code of Federal Regulations. Something that might be confusing for those familiar with the older system is that red-and-white striped buoys now have the opposite meaning — they are safe water marks, meaning there are no obstructions on all sides of it, as Boat Ed explains.

Not every buoy that looks black and white carries the same meaning. Remember that the inland waters obstruction mark has vertical stripes, with the white stripes wider than the black ones. If you see a black-topped white buoy, Federal Regulations state that this is a cardinal mark, signaling that boaters should pass to the north or east of it. A red-topped white buoy means boaters should pass to the south or west. Buoys with black and red horizontal stripes indicate localized danger that should be passed with caution, per the BoatU.S. Foundation.

Whether you're exploring a quiet Western mountain lake or the underrated lake towns of the Midwest, if you come upon an obstruction mark, slow down and give the buoy a wide berth on its open-water side. The U.S. Coast Guard advises boaters to stay on the lookout and travel at a safe speed that allows you to adjust your course well ahead of other boats, potential hazards, and navigational buoys. If you plan to hop off the boat for some freshwater snorkeling, read up on the steps to plan a perfect snorkeling vacation.