diver down flags – Everything You Need To Know

A diver down flag signals to nearby vessels that there are scuba divers below the water.

The aim of using a dive flag is of course, safety. For those who understand the flags meaning it is a clear signal that divers are in the area and to maintain a minimum safe distance.

There are two different types of divers down flag and in this post I’ll explain the difference between them, how and when to correctly display them, and the benefits (and drawbacks!) of using them.

What Is A Diver Down Flag

divers down flag

Divers are at a high risk of collision or accident caused by propellers when they are at the surface of the water, or whilst they are beginning their descent/finishing their ascent from a dive.

In order to try prevent these types of accidents a dive flag should be used to notify nearby boaters and watercraft about the presence of scuba divers within the water.

The laws surrounding dive flags and their use can vary from state to state, and from country to country but their use is often required by law.

The Two Types Of Diver Down Flags

There are two types of diver down flags to be aware of. Depending on where you are and do most of your diving, you may be much more familiar with one divers down symbol than the other.

Red & White Dive Flag

red and white scuba flag

The red and white diver down flag signals that there are divers in the water, it’s white with a diagonal stripe running top left to bottom right, and is most commonly used in the US, Canada and countries where US divers commonly frequent such as the Caribbean.

The red and white diver down flag is so synonymous with scuba diving, especially in North America, that it is essentially now known as the symbol of scuba diving, and is often displayed by dive shops selling or renting dive gear.

In most states divers are required by law to display a diver down flag when diving or snorkeling, and display of the flag will either be from the dive boat, a buoy, or both.

Alpha Flag

blue and white alpha flag

The Alpha flag (blue flag with a white diagonal stripe) is just one of many nautical signal flags. These signal flags are internationally recognised and used and by vessels in order to communicate messages with each other.

Each flag has its own specific meaning, or groups of flags can be hoist together to spell out a message.

The flag signifies to other vessels that their mobility is restricted and others must yield the right of way to them in order to avoid collision.

The alpha flag may also be used in conjunction with the red and white diver down flag when divers are in the water and passing vessels must keep well clear and at a low speed as they pass by.

When diving recreationally in the US, the red and white dive flag is the flag that is most widely recognised and used.

In the UK, most European countries and Australia/New Zealand, the Alpha flag is the more commonly used of the two flags.

Diver Down Flag Rules

Specific rules and regulations of the divers down symbol can vary so it’s important to check those specific to the area in which you’re diving before you head out into the water.


  • Stay with 300 feet (90 meters) of the diver down flag in open waters
  • Stay with 100 feet (30 meters) of the diver down flag in rivers, inlets or navigational channels
  • Aim to surface within 150 feet (45 metres) of the diver down flag
  • The Red and White dive flag when flown from a vessel should be at least 20 inches by 24 inches and flown from the vessel’s highest point
  • When displayed from a buoy, the flag should be at least 12 inches by 12 inches
  • The flag must be not be flown when divers are not in the water, or to/from the dive site


  • Maintain a distance of at least 300 feet (90 metres) from divers down buoy/flag when in open water
  • Maintain a distance of at least 100 feet (30 metres) from diver down flags/buoys when in rivers, inlets or navigational channels
  • Dive vessels displaying the flag must be not fly it when divers are not in the water, or to and from the dive site
  • A rigid flag must be used and is important that it remains fully unfurled and is still visible in calm & non-windy conditions.
  • The flag must be prominently visible on the boat.
vessel displaying a diver down flag

Which Dive Flag Should You Use

For diving recreationally in North America then the red and white diver down flag is going to be the flag most widely used and recognised, and required by law in most states.

In Europe and the UK the Alpha flag is more widely recognised would be the more appropriate of the two. 

Some people for the avoidance of any doubt choose to fly both flags.

The Problems With Diver Down Flags

The trouble surrounding dive flags has always been that non scuba divers, casual boaters and your average Joe on a jet ski probably have no idea what they mean.

The consequence of this can cause a severe risk to divers as the flag, when no-one understands its meaning are therefore unable to comprehend the dive flag rules they are supposed to be recognising

Failure to recognise what a dive flag means can sometimes even lead to watercraft often getting closer to the dive buoy in order to further inspect it!

Of course all this does not mean that you shouldn’t therefore use one – As previously explained it is required by law in most states and in many countries. 

Choosing to not fly a dive flag would clearly put yourself at more risk than by not flying one, and will often incur you a fine.

Other Similar Warning Devices

divers down warning device

Another divers down symbol that is a similar warning device to that of a flag is a delayed surface marker buoy (DSMB).

Diver’s will release their DSMB whilst still under the water’s surface. (Usually whilst performing their safety stop).

It will signal their location to the dive boat so that they are able to come and pick the divers up, whilst also serving as a divers down warning device.

The Bottom Line

Dive flags and buoys are an important piece of scuba safety equipment and in many places required by law that you fly one.

Simply knowing what a dive flag looks like and what it means for divers and people operating watercraft is half the battle, so the importance of education on this matter cannot be understated!

In the interest of safety you should always ensure you remain vigilant when diving and scan for surface activity when you’re at or near the surface of the water.

Divers alert network, aka DAN have a really good and informative article specifically on this subject that is also worth reading.

Diver down flag

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Gia Halliday

Hey, my names Gia! My biggest passions are food, travel and basically anything to do with being in the water. Combine all of that with an addiction for buying gear and you end up with with this website!