I was at a YMCA pool doing business with the manager when an alarm went off. We were close to the pool, and the lifeguard had pulled it to get attention. She was a tiny little thing, and a 6'4" guy was seizing face down in the pool. She had no idea what to do. It was during the morning, and the place was pretty empty, no one else in the pool. The manager also looked like a deer in the headlights. I used a shepherds hook to pull him close to the edge, and held his head above water about 5 minutes until EMS got there.
I had stopped keeping track of how many people I've pulled out of the water or saved by then, but that was a memorable one.