Final answer:
The primary function of a dive flag is to warn boaters that there are divers in the area.
Step-by-step explanation:
The primary function of a dive flag is to warn boaters that there are divers in the area. The dive flag is a safety device used in scuba diving and snorkeling to indicate the presence of divers in the water. It is usually a red flag with a white diagonal stripe which signals to boaters to proceed with caution and keep a safe distance from the divers.