How to read buoy markings

How to Read Buoy Markings

If you’ve spent any time at all on the water, chances are you’re used to seeing diffrent types of buoys. Considering you’ve landed on this page, it’s probably safe to say you’ve even seen a few buoy markings and thought to yourself (or maybe even out loud) “What does that buoy mean?”. Truth be told, buoys are the language of the seas, communicating vital navigation and safety information. As with learning any new language, discovering unfamiliar communication is far from uncommon. Even if you consider yourself the boss of the boat launch or the legend of the lake, brushing up on buoy markings and their meanings is always a good idea. Read on to uncover all you need to know about buoy markings!

Understanding Buoy Marking Shapes

When it comes to deciphering special-purpose buoys, the first thing you need to understand is the meaning behind the four different shapes that appear on the buoy marking labels. Always orange with a white background and sandwiched between two horizontal orange bands, these highly visible shapes universally communicate important cautionary information to boaters. So, what do these individual shapes tell us? Let’s find out!

What do buoy markings meanWhat do buoy markings mean

1. Square Buoy Marking 

If you see a white buoy with an orange square, there’s no need to sound the alarm. Square buoy markings simply convey information of interest to mariners. These informational markers could be indicative of places to find supplies, food, changes in traffic patterns or other non-regulatory information important to boaters.

2. Circle Buoy Marking 

Beacons that feature an orange circle are known as control buoys. If you happen to cruise past one, you may want to pump the brakes, as these buoy markings indicate an area where boating is restricted. For example, the orange circle could be accompanied by a posted speed limit or the image of a jet ski, indicating that the area is meant for personal watercrafts only. Whatever the case, you must obey the restriction for the safety of everyone on the water.

3. Diamond Buoy Marking 

When an orange diamond appears on a white buoy, take notice! Diamond buoy markings warn of hazards in the area. Hazard buoys may indicate anything from shallow or choppy waters to submerged hazards such as rocks, shoals or tree stumps. Orange diamond buoys should never be taken lightly. Heed the warning to avoid potentially catastrophic damage to your boat’s hull.

4. Crossed Buoy Marking 

Perhaps the most serious marker of all, an orange diamond with a cross in the middle, is called a keep-out buoy. The name says it all with this one! Obeying a crossed diamond is critical for everyone in the area. Even if it’s not readily apparent, there’s always a good reason why boating is prohibited in the area. 

Buoy Marking Messages

Now that you’re well versed in the universal symbolism of buoys, it’s time to dive deeper into the messaging behind buoy markings. While the importance of knowing the different buoy marking shapes can’t be understated, we have only scratched the surface of comprehensive knowledge necessary to prepare for maritime adventures. Here’s where we get into the nitty gritty of boat buoy messaging.

Area Closed

Boaters can easily draw a logical conclusion as to what’s going on when they see a buoy marker labeled “area closed”; the specific area or zone is off-limits to waterway users. By nature, humans are curious creatures. Rather than letting curiosity get the best of you and finding out the hard way why an area closed buoy is posted, here are some common reasons you might see this message.


  • Environmental Protection – Indicative of a protected ecological area where human activities are prohibited or limited to preserve sensitive habitats or species.
  • Military or Security Zones – The area could be serving as a testing site for military operations, a water rescue or even a police investigation.
  • Temporary Hazards – A temporary hazard could be anything from submerged objects and underwater obstructions to extreme weather events that make for treacherous waters.
  • Special Events – Popular waterways may close during certain events such as boat races, regattas and water sports competitions. Keeping these areas restricted to participants only is a critical safety measure.


The word “danger,” coupled with a bright orange diamond that we now know is alerting us to a hazard, seems rather ominous. Truthfully, the statement has a lot of ambiguity. When faced with one of these buoy markings, it’s best to heed the warning and adjust your course accordingly. While information on the exact danger lurking below can be found on up-to-date nautical charts, here are a few of the most common reasons:

Danger Buoy MarkingDanger Buoy Marking
  • Submerged Hazards – As we’ve mentioned before, this style of buoy may indicate the presence of submerged rocks, shoals or other sharp objects ready to damage your hull.
  • Low-Head Dams – Built to raise the water levels of rivers and streams, these underwater obstacles can cause small boats to become caught in a whirlpool. Always portage around low-head dams to avoid devastating consequences.
  • Strong Currents or Undertows – Most commonly found in oceans, gulfs and other waters that experience significant tidal changes, boaters and swimmers alike must practice extreme caution when alerted to the risks of dangerous riptides. 

Danger Keep Out

Commonly seen in controlled-access areas, danger keep out buoy markings are put in place to ensure public safety as well as national security. A number of different scenarios call for this style of buoy warning, some of which are temporary, like a high-profile event, while others, such as power plants and dams, are permanently off limits. Here are some specific examples of where you can expect to see a danger keep out warning:

Danger Keep Out Buoy MarkingDanger Keep Out Buoy Marking
  • Naval Vessel Protection Zones – Established to maintain the integrity and security of naval operations, these designated areas around U.S. naval vessels come with strictly enforced guidelines. If you ever find yourself in one of these areas, it is essential to maintain a distance of at least 100 yards from the ship and, when within 500 yards, operate at the lowest possible speed. Failing to obey these parameters is a felony offense.
  • Commercial Ports – Found along coastlines, commercial seaports are vital hubs for international trade, commerce and tourism. Ignoring the keep-out warning will put you and your cuddy cabin in dangerous territory alongside cruise ships, cargo carriers and commercial fishing boats.  

Danger Rocks

When you happen upon a buoy labeled danger rocks, it comes as no surprise that submerged rock formations are nearby. However, without the aid of depth sounder equipment, how can you be sure you won’t run into trouble before it’s too late? One way to locate dangerous rocks is by consulting navigational charts provided by local maritime authorities. Another way is to be aware of the common types of areas where dangerous rocks are known to exist. Here are some of those places:

Danger Rocks Buoy MarkingDanger Rocks Buoy Marking
  • Coastal Areas – Coastlines in rocky or rugged regions are notorious for their rocky outcrops that extend into the water. Use caution near cliffs and headlands, where dangerous rocks are almost always prevalent.
  • Channels and Straits – Proceed with caution when maneuvering through these narrow waterways. Due to the natural geography of passages between landmasses, hazardous underwater rock formations are known to wreak havoc.
  • Reefs – By design, reefs are comprised of sharp, jagged coral and rock formations. You can find these underwater ecosystems hidden in shallow waters, causing unsuspecting boaters to run aground. The result? Irreparable damage to your hull, keel or other parts of the boat.

Hazard Area

Hazard area buoy markings are another ambiguous warning that can leave boaters with more questions than answers. As the name suggests, these navigational aids are put in place to warn mariners about specific navigational risks in the area that have the potential to cause some serious damage. While it’s important to follow their guidance and navigate with caution for the safety of both boaters and the marine ecosystem, you can never be too informed. Here are some situations in which you may come across a hazard area buoy:

Hazard Area Buoy MarkingHazard Area Buoy Marking
  • Environmental or Ecological Concerns – Hazard areas may be designated in bodies of water with sensitive ecosystems. Critical for their biodiversity, these fragile habitats range from Mangrove forests that protect coastlines from erosion to Seagrass meadows in the Florida Keys, where many marine life call home.
  • Shallow Water – As climates vary from year to year, once popular boating destinations may experience lower than average water levels. Hazard area buoys are used to call out shallow areas or sandbars, signaling boaters to navigate around them to prevent damage to their vessels.

Idle Speed

Idle speed buoy markings are to waterways what speed bumps are to land travel. Commonly seen in areas that benefit from calm waters, idle speed buoys indicate to boaters that they need to slow down and operate at a minimal speed. The goal here is to create the least amount of wake disturbance for safety reasons and to promote an environmentally friendly boating experience. Idle speed buoys can be found in areas such as: 

Idle Speed buoy markingIdle Speed buoy marking
  • Swimming or Beach Areas – In areas where beachgoers relax and unwind in the sun, idle speed buoys are used to ensure the safety of those in the water. Too many boats creating waves can lead to hazardous conditions for unsuspecting swimmers. Regulations vary by region, but a good rule of thumb is to idle speeds within 150 ft. of designated swimming beaches.
  • Coastal Communities – Day in and day out, the hammering of boat wakes upon unprotected shorelines leads to damaging erosion. In fact, even installing seawalls is only a temporary fix to a long-term problem for waterfront property owners. Obeying idle speed markers is an important factor in helping to keep coastal wetlands intact, supporting the seafood market and water quality that depend on them.
  • Marinas and Docks – Controlling navigation is of the utmost importance around harboring and mooring areas. Reducing the wake created by boats greatly reduces the risk of collisions with other vessels and docks in the area. 

Keep Out

Our first on the list of crossed diamond buoy markers, the meaning behind keep-out buoys is a no-brainer. However, knowledge is power! Let’s review some of the places where buoys featuring a keep-out label are commonly placed so you can avoid running across them all together.

Keep out buoy markingKeep out buoy marking
  • Safety Zones – Used to mark designated safety zones, keep-out buoys communicate to boaters that waters around places where potential strong currents and submerged hazards lurk such as power plant intakes, dams and underwater telecommunication cables, to name a few.
  • Wildlife Sanctuaries – Boating, fishing and anchoring can pose a threat to certain sensitive ecosystems. Keep-out buoys are often used in marine reserves or parks where sustainable practices are used to safeguard marine life and preserve biodiversity.
  • Private Property – Waterfront property owners may post keep-out buoys to indicate where public lands end and their private access begins. Keep-out buoys serve as a clear indication to boaters that the area is off limits, with violators subject to trespassing charges.

Marina Entrance

Navigational buoys marking the access point to a marina or harbor are known as marina entrance buoys. Especially helpful in situations where multiple channels are present, these buoy markings leave no question as to where the correct entrance channel is located. Following any additional guidance provided beyond the entrance point is crucial to ensuring smooth, secure entry into the facilities.

No Anchorage

As you might suspect, no anchorage buoy markings indicate areas where anchoring is prohibited. Picture it: you’ve spent a long, hot day on the boat. You’re not ready to head back to port just yet, but you could use a break. Just when you’ve found what seems like the perfect spot to deploy your anchor and bust out your anchorshade, you notice one of these buoy markings, dashing your hopes of relaxing in the shade. Ensure this bad dream doesn’t become a reality by being mindful of these situations where no anchorage buoys are sure to be posted:

  • Busy Waterways – Just as you can’t park your car in the middle of a busy highway, you can’t anchor your boat in the middle of a congested waterway. Prohibiting anchorage regulates the flow of traffic and greatly reduces the risk of collisions. 
  • Underwater Infrastructure – From underwater oil and gas pipelines to internet cables, the world as we know it depends on undersea connectivity. While it’s easy to take an out of sight, out of mind approach to technology anchored to the ocean floor, not all underwater infrastructure is set deep in the ocean. For example, high-voltage power lines are often found close to shore. Even large lakes and rivers are not exempt from housing major transmission cables. Heed the warning not to anchor in these areas in order to protect the safety and integrity of these critical structures.
  • Vulnerable Marine Ecosystems – As we’ve mentioned before, boating can have a damaging effect on protected marine environments such as coral reefs, mudflats and oyster beds. Anchoring in any of these areas poses an even greater risk, as it has the potential to destroy or uproot endangered habitats.

No Boats

You’d think a no boats buoy marking would mean exactly that, but that’s not always the case. To understand the exemptions to the rule, you must first take note of why boating is prohibited in the area to begin with. Like we’ve discussed previously, environmental protection areas are often off limits to boaters. Along those same lines, boats may be prohibited to reduce noise disruption in areas that prioritize peace and tranquility. This begs the question: what about kayaks, canoes and other non-motorized vessels? Are they included in the no boats mandate? In some instances, yes, they are all-encompassing. However, because kayaks and canoes create less disturbance and generally have a minimal impact on the environment, they are often exempt from restrictions. It’s always best to clarify with local authorities for the most up-to-date information regarding the waterway in question. Other areas in which we can confidently say there are no exceptions to the rule include the following:

No Boats Buoy MarkingNo Boats Buoy Marking
  • Navigational Hazards – Everything from underwater rock formations to shallow waters and strong currents falls into this category. In fact, navigating treacherous waters in a non-motorized boat is even more dangerous, reiterating the importance of knowing the “why” behind the sign.
  • Preservation of Historical Sites – While not common, underwater ruins and archeological sites do exist. It may seem exciting to visit these hidden wonders, but you’ll have to take up scuba diving to experience ones that are open to the public. 

No Swimming

Put in place to protect swimmers from dangerous situations, no swimming buoy markers are not to be taken lightly. Maritime authorities seek to maintain areas of enjoyment for all water activities. If a no swimming sign is posted, it’s for a good reason. Some of which are obvious, like strong currents or hazardous underwater conditions, while one less common reason is as follows:

No Swimming Buoy MarkerNo Swimming Buoy Marker
  • Water Quality – Concerns about poor water quality due to pollution, bacteria or other foreign contaminants will sometimes cause popular swimming destinations to close. For example, toxic algal blooms known as red tide are harmful to both marine life and humans. 

No Trotlines

You may have seen a no trotline buoy marking and wondered what exactly is being prohibited here, especially if you’re not an avid fisherman. Trotlines are a commonly used type of fishing gear comprised of a length of rope with several baited hooks evenly spaced apart. Designed to span large areas of water, trotlines are generally affixed to anchor points on either side of the shore. Trotlines are often banned from areas for the following reasons:

  • Navigational Safety – Heavily traveled areas are no place for trotlines. Not only will the contraption likely fail, but it poses a significant risk to boater safety. Smaller boats may become entangled in the line, while others may cause a collision trying to avoid it.
  • Fair Access to Fishing Resources – Overuse of trotlines can undermine conservation efforts as well as cause unsuccessful fishing trips for anglers utilizing different methods. In order to ensure equitable access and sustainable fishing practices, trotlines need to be regulated.

No Watercrafts

While no boat buoy markings and no watercraft buoys serve a similar purpose of prohibiting entry or operation of vessels in designated areas, there is a distinction between the two. Earlier, we mentioned that no boat buoys may not apply to non-motorized boats such as kayaks or canoes. No watercraft messaging encompasses the whole scope of vessels, regardless of propulsion method. So, if the two buoy markings serve the same purpose for the same reasons, why the distinction? Generally speaking, it all boils down to what local ordinances and waterway management organizations have decided to establish and enforce.  

No Watercraft Buoy MarkingNo Watercraft Buoy Marking

PWC Area

Indicative of areas specifically designated for the operation of personal watercrafts (PWCs), including jet skis, wave runners and water scooters, PWC area buoy markings are often found in large lakes and coastal waters as a way to provide watersport enthusiasts with a safe, controlled environment away from the dangers of larger vessels. Key features of PWC areas include:

  • Regulations – Most PWC areas have specific rules and regulations that dictate speed limits, distance restrictions between other watercrafts and boundaries, all to ensure the safety and separation of everyone involved.
  • Enjoyment – The controlled environment of PWC areas provides riders with fewer hazards. These already established waters have been vetted for depth, lack of sensitive ecosystems and underwater hazards, allowing operators the freedom to safely enjoy their time on the water. 


Typically seen at regattas, racecourse boat buoys are used to mark the boundaries around organized boat races for the safety of race participants as well as bystanders and recreational boaters enjoying a day on the water outside of the event. As the specific location of regattas is subject to change based on tidal concerns and wind direction, even the most prepared boater can stumble upon racecourse buoys. If you find yourself encountering a racecourse buoy while boating, be mindful of your surroundings and respect the boundaries set for the race. More often than not, race officials will be on standby to give instructions and warnings to boaters who unwittingly find themselves in the mix. 

Shallow Area

Serving as visual aids in helping boaters identify and avoid hazardous shallow waters, these buoy markings can be found in all types of bodies of water. We’ve already covered the dangers of entering shallow water areas, but what should you do if you find yourself entering one by accident? 

Shallow Water Area buoy markingShallow Water Area buoy marking

1.      Reduce Speed – In order to gain more time to assess the situation and react appropriately, the most important step to minimize the risk of running aground is to slow down.

2.      Remain Vigilant – Although easier said than done, remaining calm will allow you to make informed decisions based on the water depth and other surrounding buoys.

3.      Utilize Navigation Tools – Your boat’s GPS device or any navigational charts you have on hand will provide you with the safest route out of the shallow water area. Consult the tools at your disposal to check for any alternate paths or other nearby shallow areas you need to be aware of.

4.      Follow Marked Channels – When applicable, marked channels will provide a designated path through the shallow water area. These predetermined routes will avoid the shallower areas, giving you the best chance of making it out without incident.

5.      Shift the Weight – While this isn’t an option for all boats, if you can, adjust the weight distribution of your vessel to raise the hull and reduce the draft. This will help you navigate the area more smoothly.

6.      Proceed with Caution – As we’ve mentioned before, proceeding with caution is critical for navigating shallow water unscathed. Pay close attention to any changes to the color or clarity of the water and avoid any sharp turns. 

Slow MPH

Think of slow mph buoy markings as the school zones of boating. Not as heavily restrictive as the no wake zone buoys we talked about above, typical slow speed zones have a speed limit range of 5 to 15 mph. The reason is less about the damaging effects of wakes and more about ensuring safe navigation in high-traffic areas to reduce the risk of collision. 

Slow MPH Buoy MarkingSlow MPH Buoy Marking

Slow No Wake

We know what you’re thinking, we did in fact cover no-wake zones when discussing idle speed buoy markers. However, buoys that indicate to both slow down and create minimal wake are different than the idle speed buoy markings we covered previously. While they serve a similar purpose, there are a couple nuanced differences between the two.

  • The Level of Wake Allowed – Slow no-wake buoys leave room for minimal wake to be generated, while idle speed buoys require boaters to eliminate as much wake as humanly possible. Boaters in slow no-wake zones are expected to maintain a controlled speed and navigate with caution.
  • Reason for Designation – Earlier, we talked about how wakes can contribute to unsafe swimming conditions and wreak havoc on waterfront property. Slow no-wake buoys are used more as a traffic control mechanism, sort of like a blinking yellow light at an intersection. 

Swim Area

Swim area designations are put in place to not only indicate specific areas of water where swimming is permitted but also to discourage people from swimming in areas that aren’t designated as such. These areas often have lifeguards stationed there to provide an added layer of safety and surveillance. Boaters and swimmers alike need to respect and follow the boundaries set by swimming area buoys for the safety and enjoyment of all beachgoers. 

Swim Area Buoy MarkingSwim Area Buoy Marking

Frequently Asked Questions

What color buoy indicates safe waters? 

Demarcating safe, navigable water in all directions, safe water buoys are white with red vertical stripes.

What is the orange circle on a buoy? 

White buoys that feature an orange circle are signaling a controlled area. 

What color is a danger buoy? 

While hazard buoys that indicate a dangerous situation or area are white with an orange diamond, an isolated danger buoy is black with a red horizontal band.