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What is a scuba flag?

A scuba flag is a brightly colored flag used to mark the location of a diver or group of divers underwater. Scuba diving flags are an important safety measure to alert boaters and others near the water of the presence of divers below the surface. The use of dive flags allows divers to explore underwater sites while remaining visible to those above water.

Purpose of Scuba Flags

Scuba flags serve several key purposes:

  • Indicate the presence of divers underwater to boaters and watercraft
  • Mark dive locations for other divers
  • Allow dive boats to monitor divers’ locations
  • Warn swimmers and snorkelers that divers are below
  • Make divers’ locations visible to lifeguards and safety personnel

Given their bright colors, scuba flags are highly visible on the water’s surface. Their presence alerts motorized and non-motorized watercraft to steer clear of the diving area. For boaters, the flags indicate they must slow down to idle speed when approaching the flagged area.

Types of Scuba Flags

There are two main types of scuba flags:

Diver’s Flag

The red with diagonal white stripe diver’s flag is the most common. According to the international diving code, this flag indicates: “Divers down, keep clear at slow speed.” Key features:

  • Rectangular shape
  • Red background with a diagonal white stripe from the upper left corner to the lower right corner
  • Minimum size 12 x 15 inches (30 x 38 cm)

Alpha Flag

The alpha flag features:

  • Blue and white background divided diagonally
  • Blue represents the sea and the white represents the sky
  • Used to indicate a diving leader, usually a divemaster or instructor
  • Also called the divemaster’s flag

The alpha flag is less common than the red and white diver’s flag. Both flags help mark dive locations and fulfill the key purposes of scuba flags.

When Scuba Flags are Used

It is important to display scuba flags any time diving is underway. Recommended uses include:

  • Marking areas where divers are entering and exiting the water
  • Indicating the dive boat’s location when divers are in the water
  • Marking drift diving areas
  • Placing on dive buoys and floats
  • Marking underwater diving sites from boats

Flags should be displayed clearly so they are visible from all directions on the water’s surface. They should be used any time between dawn and dusk when visibility may be limited.

Scuba Flag Requirements and Regulations

Most areas have regulations regarding proper use of dive flags and markers. Common requirements include:

  • Minimum flag size of 12 x 15 inches (30 x 38 cm)
  • Flags must be bright red with a white diagonal stripe (or blue and white alpha flag)
  • Securely affixed to buoy, float, or boat so it is visible from all directions
  • Displayed any time diving activities are occurring
  • Placed within 100 feet (30 m) of divers in the water
  • Removed from water when divers are out of the water

Boaters must steer clear or operate at idle speed within 100 feet of a displayed flag. Divers should stay within 100 feet of their flag. Using a properly displayed flag is a legal requirement, not just a recommendation.

Flag Use in Different Diving Environments

Ocean Diving

In ocean environments, scuba flags are typically displayed from:

  • Dive boats
  • Floating dive platforms
  • Buoys or floats attached to anchored dive sites
  • Drift diving mid-water floats

Oceans present added risks such as currents and swells that can cause flags to shift. Using rigid floats rather than fabric flags can help maintain visibility.

Lake Diving

For lake diving, flags are often placed:

  • On the dive platform or boat
  • At the end of a swim line from shore
  • On mid-water floats for drift diving
  • At the dive site entry/exit point

Calm lake conditions allow flexible fabric flags to be securely anchored to mark locations. Floating dive platforms also work well.

Quarry Diving

Scuba flags for quarry diving are commonly seen:

  • Attached to a float at the entry/exit point
  • On boats or dock floats
  • Marking areas between dive sites

Quarries often lack currents, so flexible flags can suffice. Buddy teams may use a smaller flag attached to a float for added visibility.

Cave Diving

For cave dives, flags or markers are used:

  • At the dive site access point
  • To mark decompression stops

Permanent markers designating underwater cave routes may also be in place. Floating surface flags are not used inside caves.

Scuba Flag Etiquette and Safety Tips

To use scuba flags properly:

  • Attach flags firmly so they don’t detach or drift
  • Use proper sized flags that are clearly visible
  • Stay within 100 feet of a displayed flag underwater
  • Remove flags after exiting the water
  • Never block or obscure another diver’s flag
  • Slow down and steer clear when you see a scuba flag as a boater

Following flag etiquette helps maintain safe diving conditions. Errant flags can create confusion and lead to accidents. Boaters should always steer away from displayed scuba flags, even if divers are not visible.

Importance of Dive Flags

Scuba flags provide critical visual markings for underwater diving locations. They alert boaters to divers’ presence and help organize diving activities. Proper flag use is legally required in most jurisdictions.

Flags mark underwater sites, drift diving routes, entry/exit points and dive boats. They enable dive teams to monitor each other’s positions. Bright flag colors are readily visible on the water’s surface.

In the absence of flags, dive sites would be indistinguishable to passing watercraft. Boat traffic would continue at normal speeds, dangerously unaware of divers below. Scuba flags make the underwater environment safer.


Scuba flags are vital safety tools for recreational divers and those operating boats and watercraft. The red and white diver’s flag indicates “divers down, stay clear.” Flags must be brightly colored and sufficiently sized for visibility. They are required by law when diving is underway.

Dive flags should mark entry/exit locations, boats, submerged sites and drift dive routes. Divers must stay close to their flag, and boaters must steer away and idle their engines if approaching within 100 feet of a displayed scuba flag. Proper flag protocol is essential for safe coexistence on the water.

Scuba flags provide a warning system for the underwater environment. They allow divers to enjoy sights below the surface while remaining visible to those above. Just as road signs and signals order movement on land, scuba flags bring organization and safety to the aquatic setting. They are an indispensable part of recreational diving.