What physical skill is essential for a lifeguard to perform rescues effectively?

Swimming fast and being capable of covering long distances in the water are vital skills for a lifeguard because these abilities directly impact the lifeguard's capacity to reach someone in distress promptly. In emergency situations, every second counts, and being able to swim swiftly allows the lifeguard to minimize the risk to the person in need, as well as themselves.

Lifeguards often encounter scenarios where they must navigate through waves, currents, or even crowded water to reach those requiring assistance. Mastery in swimming not only enhances the likelihood of a successful rescue but also helps in managing the physical demands that such situations impose. This skill is fundamental since lifeguards operate in aquatic environments where swimming is the primary method of deploying rescue techniques.

Other skills listed, like performing backflips, diving deep underwater, or running long distances, while useful in certain contexts, do not directly contribute to the core responsibility of rescues in a water environment, which is where swimming proficiency is paramount.