Name a common sign of distress for swimmers.

Inability to keep their head above water is a significant sign of distress for swimmers. When a swimmer struggles to maintain their position in the water, it typically indicates they are in serious trouble. This could be due to various factors, including exhaustion, difficulty with swimming, or a medical emergency. Recognizing this sign is crucial for lifeguards and bystanders, as it allows for prompt and necessary intervention to prevent drowning or further distress.

Other signs, such as excessive splashing without calling for help, do indicate some concern but may not be as clear an indication of a swimmer's critical state as struggling to keep their head above water. A relaxed body position and splashing calmly with a smile are generally positive signs that indicate a swimmer is comfortable and in control, rather than distressed.