I just went out to put the pool vacuum on and there is a spider THE SIZE OF A SMALL PONY drowned at the bottom of the pool.

I am becoming convinced that the pool becomes some the scene of occult rituals once the cool weather comes and we all abandon it. I have fished out of it frogs, LOTS of spiders, worms and a scorpion so far this season. Are there witches skulking behind the trees while I scoop and chlorinate? Waiting for me to go back inside so they can light their candles made from rendered human fat and start calling up the devilish creatures of the night and enticing them into our swimming pool?

Seems the most likely explanation.