What does one long blast of a whistle indicate?

A long blast of a whistle is a clear signal used by lifeguards to communicate important safety information. In this context, it signifies that the pool is about to be cleared. This could be due to various safety concerns, including impending danger such as a thunderstorm, an emergency situation, or a need to evacuate the water for any reason.

Using a long whistle blast serves to capture the attention of swimmers and patrons quickly and effectively. It is distinct from shorter bursts, which may signal different messages, such as calling attention or providing normal pool notifications. The clarity of the long blast helps ensure that all swimmers are alerted simultaneously to exit the water safely and promptly.