What Are the Two Types of Diver Down Flags?

Last Updated: November 11, 2022

There is always a risk when going on a scuba trip. One of them is boat traffic above the diver. Diver Down flags are an important safety measure that must be present on diving vessels. They were created to make sure that a diver who surfaces is able to be seen by boat traffic. These flags are also used to indicate that a diver is in the water and needs assistance.

In this guide, we will brief you all about the diver down flags, their types, uses and what they look like.

What Does a Diver-Down Flag Look Like?

what does a diver down flag look like

Diver down flags or scuba flags are visible on the water surface to warn other vessels of the underwater presence of a diver. This alerts other sailors to reduce their speeds and steer clear off the diver.

The diver down meaning differs with different flags, namely – the red and white flag and the alpha flag. Typically, it is suggested that you fly both kinds of flags to make sure that all your bases get covered.

The diver down flag must be flown when diving underwater. You can flow it from a buoy or a vessel when divers are in the water. In the case of a vessel, your flag must measure 20” x 24” at a minimum while being flown from your vessel’s highest point. Alternatively, if your scuba flag is flown from a buoy, it must measure at least 12” x 12” in diameter.

What Makes Diver Down Flags Important?

A common assumption is that since divers go way deeper than boats’ reach, they do not need to take account of the surface waterway traffic. However, this is a risky assumption.

While you may be able to safely cross boats during a mid or deep-water dive, you will still be able to hear them. However, a shallower depth or near-surface dive makes you the most vulnerable to injury from passing boats. This happens because you will enter the water level of larger boats. And if a collision happens, the large boat will topple or injure you in all probability.

The Two Types of Diver Down Flags

As mentioned before, there are two types of diver down flags, each with its own meaning.

two types of diver down flags

1. Red and White Flag

The red and white flag is the most common and noticeable among the two kinds. However, recently, this flag has gone out of fashion and replaced by the one adopted by dive supply shops and retail stores.

2. Alpha Flag

The other one is the blue and white diver down flag. It has increasingly become more popular in recent years and can be spotted more often than your traditional red and white flag. It is used more commonly on vessels and indicates the presence of a person diving underwater. This hints at passerby vehicles to either slow down or avoid that region altogether.

What makes these flags widely recognized?

Long-time scuba divers are well aware of the rules and code of conduct of diving. But the nearby boats may not have the knowledge that a diver is underwater and maybe ascending anytime.

For the safety of the diver and the surface vehicle, it is crucial to have a warning sign like diver down flags. This makes sense when you understand that divers usually run on a limited supply of oxygen and need to ascend timely. And in case the diver isn’t using an air tank, they have to hold their breath which makes it impossible for them to wait while a boat is passing by.

Does Snorkeling Require Diver-Down Flags?

People often perceive that aquatic activities like snorkeling do not require diver-down flags. However, this is nothing more than a misconception and can cost you your life in extreme cases. During surface snorkeling you are also exposed to the risk of going unnoticed by oncoming jet skis or boats. The fact that most other water sports are done at a quick pace with high speed makes it even more difficult to catch sight of a floating body on water. Plus, both scuba diving and snorkeling involve wearing muted colors to avoid predators. This, in turn, makes you invisible to the passing vessels. The diver flag comes to your rescue here by making people aware of your presence.

Diver Down Flag Rules

The following are key diver down pointers you must keep in mind the next time you go diving.


While hosting a diver down flag on your boat, it must measure at least 20 inches by 24 inches. And if you need to attach the flag to a buoy, make sure it measures 12 inches by 12 inches, at the least.


It is important to attach your flag to your boat’s highest point. This would maximize its visibility. Another thing to note is that you must not put the flag in a busy area. Rather try looking for a safer place to dive with less water traffic.

General flag placement rules are as follows: In open water, divers need to stay within 300 feet or 90 meters range of the flag, while 100 feet or 30 meters while diving in inlets, rivers, or navigation channels. Moreover, divers should try and ascend within the 150 feet range of a diver down flag.

Towing a Dive Flag

  • You need to remain under the 15 meters/50 feet reach of a diver flag. Adjusting your location in the sea would thereby require you to tow two of your dive flags.
  • Use a reel to unspool the line while you dive. Care must be taken to keep the tension high since loose flags may get tangled or caught in between. You can tie a small weight to the bottom of your line to maintain tension and avoid this.
  • Check the SPG and buoyancy using your left hand while holding the line in your right hand. It is advisable that you hold the line out at a minimum of an arm’s length to avoid tangling.
  • Also, take care not to tie the line to any of the diving equipment or even yourself. This is because the flags risk getting caught and catching currents. If that happens, it is always better to let go of your line.
  • If you aim to dive and stay within one area, a rock can be used to tie the line. However, you must not disturb the existing ecosystem in doing so. You can prevent the line from unreeling and getting lose by using a double-end clip to maintain constant line length.
  • For added safety, carry an inflatable surface marker buoy to help you in case you get lost.

Summing Up

Diver down flags signify exactly what the name suggests, that a diver is underwater. The two types of diver-down flags are the red and white flag and the blue alpha flag. Both these serve common functions and vary only slightly in their use. In recent times, the blue flags have risen in popularity.

You must follow certain rules while using and towing a diver down flag. This will help you prevent tangling and secure your underwater dive from possible injuries.

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