A diver down flag is a safety signal used on boats and in the water to show that there are divers below the surface. The classic design is red with a white diagonal stripe, which is widely recognized in the United States. Displaying this flag helps alert nearby boaters to slow down and keep a safe distance, reducing the risk of accidents. If you see this flag, it's important to steer clear and be extra cautious in the area, as divers may be surfacing unexpectedly.

Choosing the right size diver down flag depends on where and how you'll use it.

• For boats, check local regulations—many areas require a minimum size, often around 20 x 24 inches.
• For personal use or smaller crafts, a compact flag like 12 x 18 inches may be suitable, but always confirm local rules.
• Larger flags are more visible from a distance, which can improve safety.

Most diver down flags come with grommets or a canvas heading for easy attachment.

1. Use a flagpole or stiffening rod to keep the flag visible, even in low wind.
2. Secure the flag to a high point on your boat, like a mast or rail, using clips, ties, or a flagpole mount.
3. Make sure the flag is unobstructed and can be seen from all directions.

To keep your diver down flag in good shape:

• Rinse it with fresh water after each use, especially if it's been exposed to saltwater.
• Let it air dry completely before storing to prevent mildew.
• Store in a cool, dry place away from direct sunlight to avoid fading.
• Check for fraying or damage before each use and replace if needed.

Yes, there are a couple of main types:

• The red flag with a white diagonal stripe is commonly used in the United States.
• The blue and white "Alpha" flag is used internationally to signal a vessel with divers down and limited maneuverability.