Which situation is NOT considered a life-threatening emergency for swimmers?

Heat cramps, while uncomfortable and potentially distressing, are generally not classified as life-threatening emergencies for swimmers. This is primarily because they are usually manageable through hydration and rest, and they do not typically lead to immediate loss of life or significant injury, unlike other conditions listed.

Unconsciousness, severe bleeding, and cardiac arrest are critical situations that demand urgent medical attention. Unconsciousness can indicate a lack of oxygen or severe medical conditions, severe bleeding can lead to shock and death if not addressed quickly, and cardiac arrest directly stops the heart's function, requiring immediate resuscitation efforts. In contrast, heat cramps are often alleviated by taking simple corrective actions, making them less severe in an emergency context.