Why You Need to Have a Diver Down Flag Whenever You Go Out

underwater scuba diving

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Underwater exploration and deep sea diving can be an invigorating and relaxing activity. However, like all hobbies, diving comes with its own special set of risks and caution. Knowledge of diving goes beyond the simple mechanics of the oxygen tank and wetsuit; divers particularly need to be aware of the potentially deadly signs of hypoxia in themselves and their diving partner. Hypoxia is a unique diving disorder specific to underwater diving. By understanding the principles of hypoxia and learning to recognize the warning signs, divers can protect themselves from deadly or irreversible side effects. Hypoxia is one of the biggest risks of death and injury to divers and can happen within a moment’s notice. Recognizing the signs of hypoxia can prevent serious effects on the body and even death.  

Even non-divers often recognize the iconic red and white diver down flag. The flag has been featured in popular culture, and it’s a rare occasion that you spend a warm and blissful day on the water without seeing one. Even though the display of the flag is a good way for divers to recognize each other and for stores to promote their services to divers, the flag actually serves a much more important purpose than simple diving recognition. The flag is actually meant to help keep divers safe from serious injury or even death. How can a simple flag have such an important job?

What Is a Diver Down Flag?

The diver down flag is a flag used on the water to let other vessels around know that there is a diver below the surface of the water and that the diver may come up at any time. The use of the flag ensures the safety of divers and helps to prevent potential collisions between divers coming up from the depths of the water and boats or other water vessels that can’t slow down quickly or stop on a dime. In addition to letting the drivers of watercraft know there is a diver, the flag lets them know to give the diver a wide berth and to lower their speed. Diver down flags can be attached to either a diver himself or to a nearby dive boat.

History of the Diver Down Flag

The red and white diver flag that is most recognizable by North Americans was invented in the early 1950s by Denzel James Dockery. Dockery quickly discovered that he needed to find a way to keep boaters a safe distance away from him during his scuba dives.

Dockery used the U.S. Navy’s red danger flag as a reference and decided to make his own flag. He added a special touch to make it more distinctive. He asked his wife to sew a white line on top of the red flag. At first, the white line was horizontal, which proved to be a problem. While the flag was recognizable, that specific flag design was already in use as the national flag of Austria. So the two of them went back to the drawing board. After some research, they chose to make the white stripe diagonal.

Even with the invention of the diver safety flag under his belt, there was still more work for Dockery to do. He needed it to be widely recognized in order for it to have any use. Dockery spent time selling and promoting his diver flag in his hometown until it caught the attention of Ted Nixon from U.S. Divers. Nixon began to purchase and widely distribute Dockery’s flag in 1956. Nixon was so instrumental in the diver flag’s adoption that he is often mis-credited with its invention.

Within a few years after Nixon began his distribution, divers adopted the use of this flag. Today, the federal government recognizes the diver flag and most individual states recognize Dockery’s white and red flag as the official diver flag.

Different Types of Flags

There are two different types of diver down flags in use in North America. The one specific to North America is Dockery’s flag, featuring a white diagonal stripe superimposed onto a red background. This is the one most commonly recognized today due to its widespread use in North America and use in popular culture. This flag is most often attached to divers rather than boats.

However, there is another diver flag that is used in North America and even internationally. In international maritime flag signals, the diver down flag is the signal flag Alpha. This flag means “I have a diver down; keep clear at a slow speed.” It is white on the left half and blue on the right and it has a triangle cut out of it at its side. The maritime diver flag is typically flown on boats and the meaning is more about avoiding a collision than ensuring a diver’s safety; but to avoid confusion, some divers and dive boats choose to fly both flags.

How Does a Diver Down Flag Work?

While the international maritime diver down flag is typically meant to be attached and flown by a dive boat, which must stay in the vicinity of the divers it is tending to, the red and white diver down flag is often attached to a person.

Most diver down flags available for purchase are stiffened so they can be seen without the presence of wind, and they usually come with a surface marker buoy or an inflatable raft so that the flag stays afloat and visible to those on the water. Divers should be attached to the flag by use of a line attached to a reel. The diver should also carry a sharp object that can be used to cut the line in the case of entanglement.

In addition to keeping divers safe from water vessels, diver down flags are useful to personnel on a dive boat so they can better keep track of the location of their divers.

What Are the Flag Regulations?

Any diving location you can possibly go to in North America will recommend that divers use diver down flags for their own safety, and in places where there is a possibility for overhead boat traffic, it is usually mandatory to do so. Use caution to only use the diver flag when it is necessary because it is illegal in many parts of North America to display this flag if there is not currently a diver in the water, and most legislation requires that the flag be removed from the water directly after the diver surfaces.

Although it is important for the flag to be removed if there is not a diver in the water, the diver down flag may be flown outside of water. It may sound strange and unnecessary at first, but this practice is most often done by shops or other point-of-sale locations to let divers know that they provide diving services or have diving gear available for purchase.

How They Help Ensure Safety for Divers

A Glimpse Into the Neptune Memorial Reef

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The diver down flag ensures safety for divers by letting the drivers of boats and other vessels know that there is a diver below the surface of the water. While the exact rules about distance and speed depend on where you are, typically the boat or vessel must stay anywhere between 50 and 300 feet away from the flag. Similarly, most North American regulations for divers specify that a diver must stay within 50 to 300 feet of the flag. The exact distance depends on where you are diving, so make sure to check in advance not only to avoid breaking a law but to make sure you are scuba diving safely.

Other Ways to Stay Safe While Diving

Diver down flags are an extremely important safety measure to implement while scuba diving, but they aren’t the only factor when it comes to diving safety. For example, there may come a time where you must come to the surface of the water without your dive flag right next to you. Obviously, this is something that should be avoided whenever possible, but if an emergency arises and you must surface away from your dive flag, make sure to listen carefully for any boat traffic and keep your eyes peeled before you come to the surface to make sure that the coast is clear.

Besides the use of a diver down flag, other necessary gear for divers includes either a dive computer or a timing device such as a dive watch. What a dive computer or a timing device can do is to make sure that you ascend to the surface of the water at a safe speed. The typically accepted maximum ascent rate is 30 feet per minute. Even in an emergency, do your best to follow this to avoid dealing with life-threatening decompression sickness caused by quick changes in pressure.


Scuba diving can be a fun activity, but there are some dangers associated with it. Whether you are scuba diving recreationally or professionally, the use of a diver down flag is extremely important in order to lower the risk of collision and the risk of sustaining serious, or even life-threatening injuries.

It is also important for those operating watercraft to be familiar with diver down flags and other maritime flag signals in order to best follow the rules of the water. Yet because not all people operating boats or other vessels are familiar with diver down flags or are even paying attention to what is happening on the surface of the water, it’s important to be alert and to use your best judgment. Even if you are using a diver down flag, always use caution when ascending from the water and make sure to use your eyes and ears to look out for watercraft before you ascend to the surface.

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