Who's in the swimming pool?

When we were staying at friends I decided to wander around the property. I came across this cement pool. It didn't occur to me at the time that it was a swimming pool, but that's what it is. The water was clear through to the bottom - if you could find a spot to see through all of the vegetation growing in and on it. With the right background music it would have made a fabulous scene in a horror film!