Why would someone put in a salt water swimming pool?

OK, fine, you *won't* discover your error.

Advantages -- if you have a dependable source of salt water -- One of my favorite pools was salt-water, at the Shek-O Country Club in Hong Kong. They drew and exchanged salt water from the South China Sea and IIRC didn't have to use complicated pool chemistry. Another peculiarity of that pool -- it didn't have a heater, it had a chiller to keep the pool water from getting too hot in the tropic climate -- Regards --

Yes, that seems logical. I find that if I keep my lungs mostly full of air, I can put my head back and float hanging down in the water with just my face breaking the surface and my hands clasped behind my back; sometimes just my nose breaks the surface. Luckily I have a big nose.

I took up surfing a few years back. I'm still pretty bad at it but it sure is the easiest way to float. Just keep a longboard under you at all times. At least until you go head over heels.