What do the red flag with a white diagonal stripe and the blue-and-white 'Alfa' flag signal?

The red flag with a white diagonal stripe and the blue-and-white 'Alfa' flag signals that divers are down in the water. This indication is crucial for the safety of both the divers and any vessels in the vicinity. When this flag is displayed, it warns boaters to keep a safe distance, as divers are active underwater and may not be easily visible.

Understanding this signaling is essential for anyone operating a boat or watercraft, as it promotes awareness of the presence of divers and helps prevent accidents on the water. Recognizing these signals contributes to safe boating practices and ensures that both the divers and other boaters are protected while they're engaging in their respective activities.