Last night, the folks behind us were enjoying their new pool. It was a nightmare that took a year and a month, but now they have an IG with a spa and waterfall, gunite. Beautiful....

But thunderclouds were gathering, we closed down, and their kids were still in there. They didn't get them out until AFTER we started hearing thunder...

Bad, bad idea. There can be dangerous/deadly static electric around the water long before the lightning bolts start. Never be in a pool when thunder is even expected, much less audible.